Methods for treating a heart valve insufficiency or stenosis

ABSTRACT

A medical device for treating a heart valve insufficiency, with an endoprosthesis which can be introduced into a patient&#39;s body and expanded to secure a heart valve prosthesis in the patient&#39;s aorta with a catheter. In an embodiment, the endoprosthesis has a plurality of positioning arches configured to be positioned with respect to a patient&#39;s aorta and a plurality of retaining arches to support a heart valve prosthesis. The endoprosthesis includes a collapsed mode during the process of introducing it into the patient&#39;s body and an expanded mode when it is implanted. The endoprosthesis may be introduced into a patient&#39;s body and expanded via a catheter. In an embodiment, the catheter has first and second slide mechanisms configured to independently manipulate first and second sleeve elements to sequentially expand the endoprosthesis from the collapsed mode to the expanded mode.

This is a divisional application of U.S. application Ser. No.11/812,095, filed Jun. 14, 2007, now U.S. Pat. No. 9,138,315, which is acontinuation-in-part of U.S. application Ser. No. 11/785,072, filed Apr.13, 2007, now U.S. Pat. No. 7,896,915; the entire disclosure of each ofthe above applications is herein incorporated by reference.

FIELD OF INVENTION

This invention relates to a medical device for treating a heart valveinsufficiency or stenosis. The medical device includes an endoprosthesiswhich can be introduced into a patient's body with minimal invasion andautomatically expanded to position and secure a heart valve prosthesisin the patient's aorta.

BACKGROUND OF INVENTION

The expression “narrowing of a heart valve and/or heart valveinsufficiency” is intended to include a functional defect of one or moreheart valves which is either genetic or has developed over time due toage or disease. A valve defect of this type might affect each of thefour coronary valves, although the valves in the left ventricle (aortaland mitral valves) are affected much more often than the right-hand partof the heart (pulmonary and tricuspid valves). The functional defect canresult in narrowing (stenosis), inability to close (insufficiency) or acombination of the two (combined vitium).

The operating principle of medical devices for treating a heart valveinsufficiency or stenosis is already generally known in the field ofmedical technology. Biological or mechanical valve models are currentlyavailable as a means for replacing human heart valves. Replacementvalves are typically stitched to the base of the native heart valve oncethe diseased valve has been removed. The procedure requires an openingto be made in the thorax to undertake this intervention, the patient'scirculation must be supported by a heart and lung machine and the heartarrested whilst the heart valve prosthesis is implanted. This is a riskysurgical intervention which places the patient at considerable risk andinvolves a long post-operative phase of treatment. In multi-morbidpatients in particular, the risk of carrying out such intervention israrely justifiable.

In more recent times, minimally invasive treatment methods have beendeveloped which are distinctive due to the fact that the interventioncan be carried out with a local anaesthetic. This option is based on theuse of a self-expanding stent carrying a collapsible heart valveprosthesis which is implanted into the human body by means of anappropriate catheter system. A self-expanding heart valve endoprosthesisof this type can be fed by means of a catheter system through a mainartery or vein to the implantation site at the heart. Once theimplantation site is reached, the endoprosthesis, such as a stent, issuccessively unfolded. Once unfolded, the heart valve endoprosthesis canbe anchored in the blood vessel, for example, with the assistance ofanchoring hooks. The actual heart valve prosthesis is disposed directlyin the proximal region of the stent or endoprosthesis.

Patent publication DE 100 10 074 A1 discloses a device for securing andanchoring heart valve prostheses which essentially comprises shaped wireelements connected to one another. Different arches are used as a meansof reliably securing and anchoring the heart valve prosthesis. To thisend, the device described in this specification has three identicalpairs of arches respectively disposed at a distance of 120° apart. Thesearches are connected to one another by fixed body joints which assumethe function of pivot bearings. Arches bent in the opposite directionare also provided, forming lever arms which are of identical length asfar as possible, to enable a reliable seating of the arches, even in theevent of peristaltic movements of the heart and blood vessel, and afforda reliable seal for an implanted and secured heart valve prosthesis.

With the known solutions there is still a risk of heart valves beingincorrectly implanted. In particular, the heart valve prosthesis must beexactly positioned and longitudinally oriented. This requires enormousskill on the part of the surgeon performing the treatment to position astent carrying a heart valve prosthesis at its proximal end accuratelyenough in the vicinity of the patient's diseased heart valve to ensureboth correct lateral and longitudinal positioning of the heart valveprosthesis.

Amongst other things, incorrect or sub-optimal implantation andpositioning of a heart valve prosthesis can lead to inadequate sealingor valve insufficiency which places considerable stress on theventricle. For example, if a heart valve prosthesis is implanted too farabove the actual heart valve plane, this can reduce or even cover andblock the outlets of the coronary vessels (coronaries) leading to fatalcoronary ischaemia due to heart infarction. Thus, it is absolutely vitalthat the requirements of both lateral and longitudinal positioningaccuracy of a heart valve prosthesis are met.

In the case of conventional minimally invasive implantation techniqueswhere self-expandable heart valve prostheses are introduced to theimplantation site at or in the heart through a main artery of thepatient, the prosthesis is usually introduced by means of a guide wireand with the aid of catheters. In such a case it is standard practice touse a balloon catheter to expand and open the native heart valves toallow insertion of a catheter. Although it is possible to monitor andcontrol the introduction process during such an intervention, forexample with the aid of an X-ray system (heart catheter laboratory=HCL)or with the aid of ultrasound (trans-oesophageal echocardiagram=TEE),the heart valve prosthesis is still of relatively large dimensions inspite of being minimised whilst it is being introduced. It is often notpossible to obtain the required positioning accuracy due to restrictedability to manoeuvre, and in particular to ensure correct longitudinalpositioning, of the heart valve prosthesis to be implanted with thefixing elements attached to it. If there is a risk that the coronaryvessels might close, implanting the heart valve prosthesis in a positionangularly offset from the optimum implantation site represents aparticular risk for the patient.

When designing a heart valve prosthesis, allowance must specifically bemade for the considerable forces which act on the prosthesis, includingduring the filling phase of the heart cycle (diastole). Reliableanchoring is necessary to prevent the implanted heart valve prosthesisfrom becoming detached or moving in any direction.

Accordingly, it must be possible to manoeuvre the heart valve prosthesisin the relevant access vessel as efficiently as possible during theimplantation process to ensure optimum positioning accuracy on the onehand and, on the other hand, the implanted heart valve prosthesis mustbe firmly anchored at the implantation site effectively to prevent theprosthesis from subsequently shifting.

Known devices used for the transvascular implantation of heart valveprostheses are often not suitable for easy implantation of a heart valveprosthesis due to the required degree of positioning accuracy.Furthermore, until now it has only been possible to correct anincorrectly positioned heart valve prosthesis that has already beenpartially implanted with great difficulty—if at all.

These problems have been overcome by means of the medical device of thepresent invention which has an integral structure cut from a metal tubeto provide features that allow accurate positioning and firm anchoring.

SUMMARY OF THE INVENTION

In a first embodiment of the invention, a self expandable endoprosthesisfor treating a heart valve insufficiency is provided, wherein theendoprosthesis comprises at least one retaining means for manoeuvringthe endoprosthesis into and out of position within the patient.

In a particular aspect of the first embodiment the self-expandableendoprosthesis has a plurality of positioning arches for positioning theendoprosthesis in position within a patient and an anchoring segmentwith retaining arches for accommodating a prosthetic heart valve,wherein the positioning arches and retaining arches have a co-operativeshape to hold the flaps of an incumbent heart valve between thepositioning and retaining arches when the endoprosthesis is in situwithin a patient.

The present invention resides in a medical device which comprises aself-expandable endoprosthesis (hereafter referred to simply as stent)which includes a valve-supporting anchoring segment for theaccommodation of a heart valve prosthesis. The stent has a minimisedconfiguration in a first mode that allows the stent to be introducedinto the heart by way of a catheter. The stent is ‘programmed’ torespond to a stimulus that allows the stent to expand to a second modehaving an open or expanded configuration. The stent design isdistinctive due to the fact that the stent is provided with at leastthree positioning arches that project radially outwards from the planeof the stent. The positioning arches take up an open position when theendoprosthesis assumes its second pre-definable mode and, when in situwithin the body, sit in the pockets of the native heart valve. Correctpositioning of the stent is thus determined by the siting of thepositioning arches in the valve pockets which the surgeon should be ableto feel.

In co-operation with the anchoring segment, the positioning archesengage the original (old) flaps of the heart valve that are to bereplaced, resulting in an automatic fixing and positioning of themedical device regarding axial rotation on one hand and the horizontalposition on the other hand. Thus, the stent is anchored by means of botha radial force imparted by the design and functional properties of thestent, and a clipping action in a manner similar to a paper clip, withthe positioning arches on one side for the heart flaps and the anchoringsegment on the other. The native heart valve flaps act as a seal andsubstantially minimise undesirable leakage of blood around the stent.While the device is referred to herein as a stent, it may also bethought of and referred to as a valve clip, within the frame of which areplacement valve is located.

It will be appreciated that while the device of the present inventionmay be used to replace native heart valves, the device may also be usedto replace a failing biological prosthesis. Because the device of thepresent invention clips onto the valve flaps already in place, thedevice can be inserted within an existing stent without modification orremoval of the existing stent.

Since the endoprosthesis (stent) of the medical device has a continuousstructure cut from a metal tube incorporating the positioning arches onthe one hand and the anchoring segment with retaining arches on theother hand, the endoprosthesis can be made particularly inexpensivelyand in large numbers. Specifically, it would be conceivable to cut thestent structure from a metal tube by means of a laser, after which thestructure is subjected to an appropriate shaping and heat treatmentprocess so that the endoprosthesis can be transferred from a minimisedstate during implantation to an expanded state at the implantation site.This shaping and heat treatment process is advantageously operated in aseries of steps to prevent damage to the stent structure.

Since the endoprosthesis of the medical device has a continuousstructure cut from a metal tube each retaining arch is associated with apositioning arch, and every end portion of the positioning arch at thedistal end of the endoprosthesis is joined to the terminal portion of anassociated retaining arch. Thus, there is no need to provide fixed bodyjoints or similar connecting devices and the complexity of theendoprosthesis is much reduced. Expressed in another way, theendoprosthesis of the medical device proposed by the invention is astent or clip which, on the one hand, offers a positioning function dueto positioning arches having a minimal longitudinal extension and, onthe other hand, provides the function of retaining a heart valveprosthesis due to the retaining arches.

As will be seen, when transferring the endoprosthesis from the firstpre-definable mode to the second pre-definable mode by widening thecross-section of the entire stent, the retaining arches on the one handand the positioning arches on the other hand are opened out in a radialdirection. The second mode of the endoprosthesis is advantageouslyselected so that as the retaining and positioning arches open up, theypress against the vessel wall of the aorta and form a positiveconnection with it, thereby anchoring the medical device firmly at theimplantation site.

The structure of the endoprosthesis imparts a particularly short shapeto the medical device and so the medical device is particularly easy tomanoeuvre in its minimised state. This is of particular advantage if theimplantation route to the heart is via the aortic arch. The minimumlength of the medical device is made possible because every end portionof the positioning arch at the distal end is joined to the end portionof an associated retaining arch and both the positioning arch and theretaining arch extend to the proximal retaining region of the medicaldevice or endoprosthesis. The anchoring segment that accommodates theheart valve prosthesis therefore lies at the proximal retaining regionof the endoprosthesis.

Advantageous and preferred embodiments of the medical device arespecified in the dependent claims.

In one particular embodiment every positioning arch and its associatedretaining arch has an essentially U-shaped or V-shaped structure whichis closed towards the proximal end of the endoprosthesis.

In a preferred embodiment of the anchoring region or segment, it wouldbe conceivable for the anchoring segment to be of an essentiallyU-shaped or V-shaped structure which is closed at the distal end of theendoprosthesis. In such a case, the distal region of the anchoringsegment constitutes the tip of the anchoring segment and the respectivearms of the anchoring segment are joined to the respective arms of twoadjacent retaining arches at the proximal end of the anchoring segment.

Alternatively and in another embodiment, the respective arms of theretaining arches have continuous slots or elongate holes extending inthe longitudinal direction of the retaining arches. The purpose of sucha feature is to enable and assist the expansion of the endoprosthesisfrom the minimised state into the expanded state because these slots orelongate holes are preferably designed to permit a particularly easycross-sectional expansion of the stent (endoprosthesis) whilstsimultaneously reducing the length of the stent. Such slots or elongateholes have the additional advantage of saving on material.

In the case of the latter embodiment it would be conceivable for therespective retaining arches to be additionally provided with reinforcingportions which interrupt the slots extending in the longitudinaldirection of the retaining arches. These reinforcing portionsessentially prevent components of the retaining arches from projectingoutwards from the circumferential plane of the endoprosthesis when theendoprosthesis is in an expanded state.

Each positioning arch is cut from the material blank of the metal tubewhich is accommodated by the essentially U-shaped or V-shaped structureof the associated retaining arch. In this preferred embodiment of thestent structure, therefore, the respective retaining arches of theretaining segment form the proximal anchoring region of theendoprosthesis similarly, the respective positioning arches are of adesign symmetrical with the retaining arches but lie slightly in frontof the distal retaining region of the medical device. The respectivedistal ends of the positioning arches are joined to the respectivedistal ends of the co-operating retaining arches in the distal retainingregion of the endoprosthesis. When the endoprosthesis is in an expandedstate, not only the proximal anchoring region with the heart valveprosthesis fitted to it, the positioning arches disposed between theproximal anchoring and the distal retaining regions of the medicaldevice open out, but also the joining points between the respectivepositioning arches and retaining arches at the distal end of the medicaldevice. This provides a radially acting force which is applied to thevessel wall via the distal retaining region of the medical device whichfurther assists anchoring of the medical device at the implantationsite.

Since the medical device is in a (an expanded) state in which the distalretaining and proximal anchoring regions as well as the positioningarches are opened out radially when the endoprosthesis assumes thesecond mode, the expanded medical device has a shorter length than itdoes in its minimised state. To enable the length of the medical devicein its expanded state to be set beforehand, it would be conceivable toconnect the respective distal end portions of the positioning arches tothe distal end portions of the associated retaining arches using aconnecting web extending essentially in the longitudinal direction ofthe endoprosthesis rather than directly. The length of the medicaldevice in the expanded state can therefore be adapted by selecting thelength of this connecting web accordingly. However, it is preferable,especially with a view to ensuring good manoeuvrability of the medicaldevice during the implantation process, i.e. when the endoprosthesis isin its first (minimised) mode, if the connecting web between therespective end portions of the positioning arches and retaining archesis selected so that it is as short as possible.

According to a second embodiment of the invention a catheter tip isprovided, which can be disposed at the proximal end of the cathetersystem, and in which the endoprosthesis of the first aspect can beaccommodated, said catheter tip having a retaining mechanism forreleasably securing at least the distal end of the endoprosthesis in thecatheter tip.

In particular aspects of the second embodiment the catheter tip has aretaining mechanism shaped to co-operate with the retaining means on theendoprosthesis. In another particular aspect of the second embodimentthe catheter tip the retaining mechanism has a crown with at least onepocket, the at least one pocket having a shape complementary to that ofthe endoprosthesis retaining means.

In one particularly preferred embodiment of the medical device, theendoprosthesis has retaining means at its distal end which can beengaged with corresponding retaining means on an introduction cathetersystem, particularly a catheter tip or cartridge. In one embodiment ofthe retaining means, the means may be in the form of an anchoring eyedisposed between two adjacent positioning arches. In which case, thearms of the adjacent positioning arches on the one hand and the arms ofthe retaining arches associated with the adjacent positioning arches onthe other hand are connected to the anchoring eye. It would likewise beconceivable for the arms of the adjacent positioning arches to bedirectly and the respective arms of the retaining arches associated withthe adjacent positioning arches to be indirectly connected via aconnecting web extending essentially in the longitudinal direction ofthe endoprosthesis. Generally speaking, the purpose of the retainingmeans provided on the distal end of the endoprosthesis is to accommodateappropriate mechanisms on the introduction catheter system whichcomplement that of the retaining means of the endoprosthesis. Theengagement between the catheter system on the one hand and the retainingmeans on the distal end of the endoprosthesis on the other hand can bereleased by means of an external manipulation to release the medicaldevice at the implantation site, thereby ensuring that the medicaldevice expands and is thus reliably anchored. It will be appreciatedthat the retaining means may be of any suitable shape or configurationsuch as eyes, loops, fingers or imperforate heads.

The use of such retaining means enables the stent to remain in contactwith the catheter prior to full release of the stent. By maintainingcontact with the stent prior to its full release, location andimplantation position of the stent can be controlled more accurately bya physician. The functioning of the stent and heart valve prosthesis mayalso be checked and, if one or neither is functioning correctly, thephysician can withdraw and remove the stent by virtue of the retainingmeans remaining in contact with the catheter.

Problems or complications with a stent may occur post implantation. Forexample, failure of the stent to deploy properly, misalignment,dislodgement, or damage of the stent after it has been deployed may leadto valve leakage or other problems. In these cases, removal of the stentis desirable. This may be accomplished up to four weeks afterimplantation and before the stent has become integrated with theimplantation site by a covering or over-growth of cells. Therefore, inanother embodiment, the retaining means preferably have a shape orconfiguration which also allows them to engage with parts of a tool thatenables removal of the stent. Preferably the retaining means are caughtby and engage or interact with parts of the tool so that the stent canbe pulled into, for example, a catheter where the stent assumes itsfirst compressed mode and can be withdrawn from the body with minimal orno tissue damage.

As an alternative to the embodiment of the medical device outlinedabove, it would however also be conceivable for the respective arms ofthe adjacent positioning arches to be joined to the retaining meansindirectly via a connecting web extending essentially in thelongitudinal direction of the endoprosthesis. In which case, the arms ofthe retaining arches associated with the adjacent positioning arches arejoined to the retaining means indirectly via a connecting web extendingin the longitudinal direction of the endoprosthesis. The connecting webof the retaining arches merges into the connecting web of thepositioning arches at the end portion of the positioning arches.Providing the respective connecting webs for connecting the arms of thepositioning arches to the retaining means and for connecting the arms ofthe retaining arches to the end portion of the positioning arches offersa particularly simple but effective way of adapting the length of theendoprosthesis to a patient's respective requirements and does sobecause the respective lengths of the connecting webs can be selectedappropriately.

In another embodiment of the solution proposed by the invention, theretaining means may include at least one barb or hook, the tip of whichpoints in the direction of the proximal end of the endoprosthesis. Thisensures that the distal retaining region of the endoprosthesis can beretained at the implantation sit in its expanded state particularlyreliably. In this preferred embodiment, therefore, the endoprosthesis issecured at the implantation site due to the radial force exerted on thevessel wall by the endoprosthesis, in particular by the distal retainingregion of the endoprosthesis, but also due to the barb hooking into thevessel wall. It would naturally also be possible to use otherappropriate design options for the barb(s) or hook(s).

As an alternative to or in addition to the barbs or hooks, anotherconceivable way of securing the endoprosthesis reliably at theimplantation site is for the respective arms of the retaining arches ofthe endoprosthesis to be provided with an anchoring support in the shapeof a bow which projects out from the relevant arm of the retaining archwhen the endoprosthesis is in the expanded state. The tip of the bowpoints in the direction of the distal end of the endoprosthesis. Thisembodiment provides additional fixing means for the endoprosthesis andadditionally secures the medical device to prevent it from becomingdislocated after implantation.

As mentioned above, one main aspect of the invention is that theendoprosthesis is provided with retaining means at its distal end whichcan be moved into engagement with the retaining mechanism on the tip ofan introduction catheter or insertion system. In one embodiment theseretaining means are in the form of fixing eyes.

In an alternative embodiment, the retaining means comprises at least oneretaining element arranged at the distal region of the stent, the atleast one retaining element being designed to be movable into areleasable engagement with a retaining mechanism of an insertion system,such as a catheter tip. Preferably the at least one retaining elementengages with a pocket or depression formed in a crown of the retainingmechanism of the insertion system. Most preferably, the at least oneretaining element of the stent has a retaining head, having a designwhich complements at least one pocket or depression formed in the crownof the insertion system, thereby being adapted to co-operate with theretaining mechanism of the insertion system by means of an improvedreleasable engagement.

In this embodiment, there is less risk that the retaining mechanism ofthe catheter tip can become wedged or jammed with the distal region ofthe endoprosthesis. This can be achieved because neither the retainingmechanism of the catheter tip nor the retaining means of theendoprosthesis have parts that protrude from the crown of the retainingmechanism when the endoprosthesis is fixed to the catheter tip. As aresult, minimal shaking or moving of the catheter tip should be requiredto release the engagement between the catheter system and the distalregion of the endoprosthesis.

Generally speaking, the retaining means provided on the distal end ofthe endoprosthesis or stent are to be accommodated in an appropriatemechanism on the insertion catheter system. These mechanisms should beof a design complementing the retaining means of the stent. Theengagement between the retaining mechanisms of the catheter tip on theone hand and the retaining means at the distal end of the stent on theother hand can be released by means of an external manipulation torelease the stent at the implantation site and allow the stent to expandthus ensuring that the heart valve prosthesis is reliably secured.Naturally, it would also be possible to consider other solutions for theretaining means. For example, the retaining means may have differentshapes and/or profiles, being convex or concave and forming a spoon orcup shape. Profiling the retaining means in this manner allows theretaining means to remain seated in position without affecting outwardmovement, for example as the stent expands radially during its finalrelease steps. Alternatively, the retaining means may be of aball-and-socket configuration in co-operation with the retainingmechanism at the catheter tip.

In a preferred embodiment of the retaining means, it is conceivable forthe means to be provided in the form of a retaining head which isdisposed between two adjacent positioning arches. In this embodiment,the respective arms of the adjacent positioning arches on the one handand the respective arms of the retaining arches associated with theadjacent positioning arches on the other hand are joined to theretaining head. It will be apparent to one skilled in the art that theuse of such fixing means is not limited to use with the disclosed stentdesign. Such retaining means could also be utilised with other stentdesigns where reliable release of the stent from the implantation means,such as a catheter, is required.

It is important that the stent with the heart valve prosthesis can beeasily released from the catheter tip of a catheter system as soon asthe heart valve prosthesis is optimally positioned. The mechanismdescribed above has been found greatly to assist in this manoeuvre.

In a third embodiment of the invention there is provided a cathetersystem for use in treating a heart valve defect, in particular a heartvalve insufficiency or narrowing of a heart valve, in a patient, saidcatheter system comprising a catheter tip, according to the secondaspect, and further comprising a self-expandable endoprosthesis,according to the first aspect, accommodated in the catheter tip of thecatheter system, and when the endoprosthesis is accommodated in thecatheter tip of the catheter system it assumes a first pre-definablemode and outside of the catheter tip and in the implanted state itassumes a second pre-definable mode, and the endoprosthesis is in afolded state in its first mode and in an expanded state in its secondmode.

Conventional catheter systems for inserting a self-expandable heartvalve stent typically comprise a catheter tip with a retainingmechanism, the retaining mechanism being adapted for releasably securingthe distal region of the stent on the catheter tip. The catheter tiptypically has a crown with a plurality of projecting elements. Theprojecting elements of the crown are designed so as to complementretaining eyes provided at the distal region of the stent. In thisrespect, the retaining mechanism arranged in the catheter tip of theconventional catheter systems co-operates with the distal region of thestent by means of a releasable engagement. The engagement between theretaining mechanism of the catheter system, and the retaining means inthe distal region of the stent is normally releasable by means of anexternal manipulation so that the stent with the heart valve prosthesisattached to it can be released from the catheter at the implantationsite.

However, the use of retaining eyes still pose a risk that the engagementbetween the catheter system and the distal region of the stent can onlybe released by means of movement of the stent. In particular, theretaining eyes provided in the distal region of the stent may wedge withthe projecting elements which protrude from the crown of the retainingmechanism of the catheter tip. As a result, shaking and/or moving of thecatheter tip may be required to release the engagement between thecatheter system and the distal region of the stent. Such movement islikely to dislodge the stent from its desired position and may damagethe prosthesis.

Thus, there is still a risk of heart valve prostheses being incorrectlyimplanted. The heart valve prosthesis must be exactly positioned andlongitudinally oriented which requires enormous skill on the part of thesurgeon performing the treatment. On the one hand the stent must beaccurately positioned and on the other hand the stent must be releasedfrom the catheter tip accurately enough in the vicinity of the patient'sexisting heart valve to ensure both correct lateral positioning accuracyand a correct longitudinal position of the heart valve prosthesis.Amongst other things, incorrect implantation and/or sub-optimalpositioning of a heart valve prosthesis can lead to inadequate sealingor valve insufficiency which places considerable stress on theventricle. If a heart valve prosthesis is implanted too far above theactual heart valve plane, for example, this can cause the outlets of thecoronary vessels (coronaries) to close, leading to fatal coronaryischaemia due to heart infarction. This being the case, it is vital thatboth the lateral positioning accuracy and longitudinal positioningaccuracy of a heart valve prosthesis meet these strict requirements.

When such retaining heads described above are used, the catheter tip ofthe insertion system ideally includes a retaining mechanism forreleasable securing at least the distal region of the stent in thecatheter tip. Preferably, the retaining mechanism comprises a crown withat least one pocket or depression formed in the crown. The at least onepocket or depression is of a design which complements the shape of theretaining means provided on the distal region of the stent. Thus, theretaining mechanism is adapted to co-operate with the distal region ofthe stent by means of a releasable engagement. In particular, thissolution provides a reduced risk that the retaining mechanism of thecatheter tip can become wedged or jammed with the distal region of thestent. This can be achieved because the retaining mechanism of thecatheter insertion system has no parts protruding or projecting from thecrown of the retaining mechanism. As a result, there should be no needto shake or move the catheter tip to release the engagement between thecatheter system and the distal region of the stent.

In one particular embodiment, the at least one pocket or depressionformed in the crown of the retaining mechanism has a shape which isadapted for accommodating the retaining means provided on the distalregion of the stent with positive locking, thereby providing forreleasable engagement between the distal region of the stent and thecatheter tip. The at least one pocket or depression may be integrallyformed in the crown of the retaining mechanism of the catheter tip.Preferably, the at least one pocket or depression is formed as a mouldor inverse image of the retaining means of the stent even if theretaining means comprises, for example, barbs or hooks formed at aretaining head.

Preferably the crown of the retaining mechanism is generally cylindricaland the at least one pocket or depression formed in the crown has ashape adapted to completely accommodate completely the retaining meansprovided on the distal region of the stent such that there are no partsof the distal region of the stent protruding from the superficialsurface of the cylindrical crown. Hence, this preferred embodiment leadsto a catheter tip which has a very compact retaining mechanism with thesurprising advantage that the diameter of the catheter tip can bereduced.

In one embodiment, the catheter tip further comprises ‘snap-on’ meansarranged on the at least one pocket or depression formed in the crownfor releasable fixing of the retaining means in the at least one pocketor depression. Preferably, this snap-on means comprises a projecting rimor flange arranged on or near the outer edge of the at least one pocketor depression formed in the crown. The projecting rim or flange may beadapted to hold the stent retaining means in the at least one pocket ordepression. Such snap-on means, for example in the form of a clipmechanism, serves to fix temporarily the stent retaining means duringloading of the catheter tip. Preferably the snap-on means are designedsuch that the resisting force caused by the snap-on means and acting onthe stent retaining means is smaller than the radial forces acting onthe distal portion of the stent when the stent during expansion. Thishas the advantage that the snap-on means should not retard or inhibitthe stent during its final release thus ensuring efficient release ofthe stent.

In another embodiment, the crown of the retaining mechanism furthercomprises at least one groove formed therein. The at least one groove isassigned to the at least one pocket or depression and extendsessentially in the longitudinal direction of the crown from said pocketor depression to one end of the crown. The at least one groove has ashape adapted to accommodate a connecting web of the stent. Theconnecting web of the stent extends essentially in the direction of thestent and connects the stent retaining means with respective arms of thestent. Preferably, the groove associated to the pocket or depressionformed in the crown is formed as a mould or inverse image of theconnecting web or other parts of the stent, extends essentially in thedirection of the stent and connects the retaining means with respectivearms of the stent.

Of course, a catheter tip of the kind as defined above may also comprisesnap-on means arranged on the at least one groove formed in the crown ofthe retaining mechanism for releasable fixing of the stent connectingweb which connects the stent retaining means with the respective arms ofthe stent. Preferably, this snap-on means comprises a projecting rim orflange arranged on or near the outer edge of the at least one grooveformed in the crown of the retaining mechanism, said projecting rim orflange being adapted to hold the connecting web of the stent in the atleast one groove.

Thus, the catheter tip has an improved retaining mechanism forreleasably securing at least the distal region of the stent in thecatheter tip. The catheter tip can be connected to a catheter system bymeans that allow manipulation of the catheter tip. Such catheter systemsare known in the art and may, for example, comprise a handle whichfurther comprises operating means which co-operate with the catheter tipso that when the operating means are operated, the stent can be releasedfrom the catheter tip in steps in a pre-definable sequence. In addition,the catheter tip may further comprise a housing system for accommodatingat least the proximal region of the stent. The housing system preferablycomprises a first housing portion for accommodating first functionalcomponents of the stent, for example the retaining arches of the stent,and a second housing portion for accommodating second functionalcomponents of the stent, for example the positioning arches.

In a yet further embodiment, the endoprosthesis has an external diameterof approximately 5.0 mm and a length of between 33.0 mm and 40.0 mm,preferably between 34.0 and 39.0 mm, even more preferably between 34.37mm and 38.37 mm, in its first mode. This means that the medical devicecan be introduced by means of a 21F introduction system, for example,and heart valve prostheses with a diameter of 21 mm to 28 mm may beused. The length specifications given above are currently preferredvalues based on medical devices suitable for the majority of patientsrequiring treatment.

In order to obtain a particularly reliable anchoring of the implantedmedical device in its expanded state, the endoprosthesis may besubjected to a shaping and heat treatment process during its manufactureso that when the endoprosthesis is in the finished state, it has aslightly concave shape tapering in the direction of the proximalanchoring region of the endoprosthesis in its second mode. In otherwords, the proximal anchoring region of the endoprosthesis, i.e. theregion to which the heart valve prosthesis is attached, has a slightlynarrower diameter than the distal anchoring region. It has been foundthat if the distal anchoring region of the endoprosthesis in the secondmode has an approximately 10% to 25% bigger diameter than the proximalanchoring region of the endoprosthesis, radial forces are generated inparticular at the distal anchoring region of the endoprosthesis whichenables the medical device to be securely anchored in the vessel withoutcausing damage to the vessel wall. Due allowance is also made for theperistaltic movements of the heart and vessel wall. The slightly lowerradial force expended by the proximal anchoring region of theendoprosthesis not only serves as a means of anchoring the medicaldevice in the aorta but in particular also opens out the heart valveprosthesis fitted on the proximal anchoring region of the endoprosthesisand imparts to it a reliable seal with respect to the vessel wall.Naturally, however, it would also be conceivable for the concave shapeto be more or less pronounced when the endoprosthesis assumes thesecond, expanded mode.

It is preferable if the anchoring region of the endoprosthesis has adiameter of between 22 mm and 33 mm, and preferably between 25 mm and 31mm, in the second mode. This being the case, it would be conceivable forthe endoprosthesis to be made in two or more differently dimensionedsizes. In which case, an optimum size of endoprosthesis could beselected depending on the patient and the exact dimensions of theendoprosthesis adapted to the patient to be treated—starting from apre-defined stent size—by an appropriate finishing treatment of theendoprosthesis (stent), in particular by tempering.

In one, particularly preferred embodiment of the medical device, thedevice comprises an endoprosthesis (stent) and a heart valve prosthesis,preferably a bio-heart valve prosthesis, even more preferably an aorticheart valve prosthesis. The valve is attached to the anchoring segmentof the endoprosthesis by means of a thread, suture or similar. Orificesare provided in the retaining arches of the endoprosthesis through whichthe thread or similar is inserted. It would be conceivable for the heartvalve prosthesis to be connected to the anchoring segment of theendoprosthesis immediately prior to the medical intervention. As aresult, the medical device can be made in a modular design, which is ofparticular advantage in terms of transporting and storing the device. Abio-heart valve prosthesis may comprise material from a variety ofsources such as from human, bovine, equine or porcine tissue. Bio-heartvalves may be naturally occurring valves or they may be artificiallyderived or manufactured from suitable biological material, cells ortissue. Alternatively a heart valve prosthesis may be manufactured frombiologically compatible artificial materials, that is non-biologicalsources such as, for example, from pyrolytic carbon, titanium, Teflon,polyester, Dacron and the like.

As regards the preferred material used for the endoprosthesis of themedical device, a shape memory material is ideally used which isdesigned so that the endoprosthesis is transformed from one shape toanother shape by means of an external stimulus. Thus, the endoprosthesisassumes a minimised shape in the first mode (when the medical device isin the minimised state) and an open shape in the second mode (when themedical device is in the expanded state). Especially if a shape memorymaterial such as Nitinol is used, i.e. an equal atomic alloy of nickeland titanium, the implantation process will be particularly gentleduring the operation of implanting the medical device, minimising therisk of tissue damage on insertion and implantation. Another advantageof using a shape memory metal is that the open shape can be transformedback to the minimised shape simply by reversing the external stimulus.

During production of an endoprosthesis made from a shape memorymaterial, after the stent structure has been cut from the metal tube, itis deformed and fixed in the desired open shape via a process known as“programming”. This operation may be performed on the one hand byheating, deforming and then cooling the stent structure. Alternatively,the stent structure may also be deformed at low temperature by anoperation known as cold stretching. As a result, the open shape ismemorised whilst the minimised shape actually prevails. If the stentstructure is then subjected to an external stimulus, the shape memoryeffect is triggered and the memorised open shape is restored.

In a particularly preferred embodiment, the external stimulus is asettable switching temperature. It is therefore conceivable for theendoprosthesis material to be heated to a temperature higher than theswitching temperature in order to trigger the shape memory effect andthus restore the memorised open shape of the endoprosthesis. Byselecting an appropriate chemical composition of the shape memorymaterial, a specific switching temperature can be fixed before theendoprosthesis is programmed. This being the case, the switchingtemperature is set so that it falls within the range of room temperatureand the body temperature of the patient. This is of particular advantagein applications where the medical device is to be implanted in apatient's body. Accordingly, when implanting the medical device, it ismerely necessary to ensure that the instrument is not heated until it isin the implanted state on the patient's body (36° C.), at which pointthe shape memory effect of the endoprosthesis material is triggered.

Preferred embodiments of an endoprosthesis of a medical device proposedby the invention will be described in more detail below with referenceto the appended drawings:

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1a illustrates a first, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst predefined mode in which the medical device is in its minimisedstate;

FIG. 1b shows the endoprosthesis illustrated in FIG. 1a but in a statebetween its first pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 1c shows the endoprosthesis illustrated in FIG. 1a but in itssecond mode in which the medical device is in its expanded state;

FIG. 1d shows a first, preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 1c and a heart valve prosthesis attachedto it and opened out;

FIG. 1e is a flat projection of a cutting pattern which can be used forthe production of the first, preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 1a integrally from a metaltube;

FIG. 2a shows a second, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 2b shows the endoprosthesis illustrated in FIG. 2a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 2c shows the endoprosthesis illustrated in FIG. 2a in its secondmode in which the medical device is in its expanded state;

FIG. 2d illustrates a second preferred embodiment of the medical deviceproposed by the invention in its expanded state, with an endoprosthesisof the type illustrated in FIG. 2c and a heart valve prosthesis attachedto it and opened out;

FIG. 2e is a flat projection of a cutting pattern which can be used forthe production of the second preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 2a integrally from a metaltube;

FIG. 3a shows a third, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 3b shows the endoprosthesis illustrated in FIG. 3a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 3c shows the endoprosthesis illustrated in FIG. 3a in its secondmode in which the medical device is in its expanded state;

FIG. 3d illustrates a third preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 3c and a heart valve prosthesis attachedto it and opened out;

FIG. 3e is a flat projection of a cutting pattern which can be used forthe production of the third preferred, self-expandable endoprosthesis tocut the endoprosthesis illustrated in FIG. 3a integrally from a metaltube;

FIG. 4a shows a fourth, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 4b shows the endoprosthesis illustrated in FIG. 4a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 4c shows the endoprosthesis illustrated in FIG. 4a in its secondmode in which the medical device is in its expanded state;

FIG. 4d illustrates a fourth preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 4c and a heart valve prosthesis attachedto it and opened out;

FIG. 4e is a flat projection of a cutting pattern which can be used forthe production of the fourth, preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 4a integrally from a metaltube;

FIG. 5a shows a fifth preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 5b shows the endoprosthesis illustrated in FIG. 5a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 5c shows the endoprosthesis illustrated in FIG. 5a in its secondmode in which the medical device is in its expanded state;

FIG. 5d illustrates a fifth preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 5c and a heart valve prosthesis attachedto it and opened out;

FIG. 5e is a flat projection of a cutting pattern which can be used forthe production of the fifth, preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 5a integrally from a metaltube;

FIG. 6a shows a sixth preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 6b shows the endoprosthesis illustrated in FIG. 6a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 6c shows the endoprosthesis illustrated in FIG. 6a in its secondmode in which the medical device is in its expanded state;

FIG. 6d illustrates a sixth preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 6c and a heart valve prosthesis attachedto it and opened out;

FIG. 6e is a flat projection of a cutting pattern which can be used forthe production of the sixth, preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 6a integrally from a metaltube;

FIG. 7a shows a seventh, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 7b shows the endoprosthesis illustrated in FIG. 7a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 7c shows the endoprosthesis illustrated in FIG. 7a in its secondmode in which the medical device is in its expanded state;

FIG. 7d illustrates a seventh preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 7c and a heart valve prosthesis attachedto it and opened out;

FIG. 7e is a flat projection of a cutting pattern which can be used forthe production of the seventh preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 7a integrally from a metaltube;

FIG. 8a shows an eighth, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 8b shows the endoprosthesis illustrated in FIG. 8a in a statebetween its first, pre-definable mode and its second mode in which themedical device is in its expanded state;

FIG. 8c shows the endoprosthesis illustrated in FIG. 8a in its secondmode in which the medical device is in its expanded state;

FIG. 8d illustrates an eighth preferred embodiment of the medical deviceproposed by the invention in its expanded state with an endoprosthesisof the type illustrated in FIG. 8c and a heart valve prosthesis attachedto it and opened out;

FIG. 5e is a flat projection of a cutting pattern which can be used forthe production of the eighth preferred, self-expandable endoprosthesisto cut the endoprosthesis illustrated in FIG. 8a integrally from a metaltube;

FIG. 9a shows a ninth, preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itsfirst, pre-determined mode in which the medical device is in itsminimised state;

FIG. 9b is a perspective side view of a connecting web between an endportion of a positioning arch and an end portion of an associatedretaining arch of the endoprosthesis illustrated in FIG. 9a in itssecond mode in which the medical device is in its expanded state;

FIG. 9c is a perspective side view of a positioning arch and theassociated retaining arch of the endoprosthesis illustrated in FIG. 9ain its second mode in which the medical device is in its expanded state;

FIG. 9d is a perspective plan view of the distal region of theendoprosthesis illustrated in FIG. 9a in its second mode in which themedical device is in its expanded state;

FIG. 9e is a flat projection of a cutting pattern which can be used forthe production of the ninth preferred embodiment of the self-expandableendoprosthesis to cut the endoprosthesis illustrated in FIG. 9aintegrally from a metal tube;

FIG. 10 is a flat projection of a cutting pattern which can be used forthe production of another preferred embodiment of the self-expandableendoprosthesis to cut an endoprosthesis integrally from a metal tube;

FIG. 11 shows another preferred embodiment of a self-expandableendoprosthesis for the medical device proposed by the invention in itssecond mode in which the medical device is in its expanded state;

FIG. 12a shows a twelfth preferred embodiment of a self-expandable stentin its first, pre-determined mode in which the stent is in its minimisedstate;

FIG. 12b shows the stent illustrated in FIG. 12a in a state between itsfirst, pre-definable mode and its second mode in which the stent is inits expanded state;

FIG. 12c shows the stent illustrated in FIG. 12a in its second mode inwhich the stent is in its expanded state;

FIG. 12d shows the stent illustrated in FIG. 12c with a heart valveprosthesis attached to it and opened out;

FIG. 12e is a flat projection of a cutting pattern which can be used forthe production of the twelfth preferred embodiment of a self-expandablestent to cut the stent illustrated in FIG. 12a integrally from a metaltube;

FIG. 13a is a schematic view intended to illustrate one possibleimplantation operation of the medical device proposed by this invention;and

FIG. 13b is a schematic view of the medical device proposed by theinvention in the implanted state.

FIGS. 14a to d illustrate a preferred embodiment of the insertion systemof a transapical design proposed by the invention as a means ofinserting a self-expandable heart valve stent in its four pre-definablefunctional modes with a view to illustrating the procedure of loading astent in the insertion system;

FIGS. 15a to d shows the embodiment of insertion system illustrated inFIG. 14 in its four pre-definable functional modes with a view toillustrating the procedure whereby a stent accommodated in the insertionsystem is released;

FIG. 16a shows a side view of a first preferred embodiment of theretaining mechanism disposed in the catheter tip of the insertion systemproposed by the invention;

FIG. 16b is a view in cross-section of the retaining mechanismillustrated in FIG. 16a , seen along line A-A indicated in FIG. 16 a;

FIG. 16c is a plan view of the distal retaining region of a stent, whichcan be retained by means of the retaining mechanism illustrated in FIG.16 a;

FIGS. 17a to b illustrate a preferred embodiment of the medical deviceproposed by the invention with an insertion system of a transapicaldesign, for example illustrated in FIG. 14 or FIG. 15, and aself-expandable heart valve stent in different functional modes of theinsertion system;

DETAILED DESCRIPTION

A first preferred embodiment of the self-expandable endoprosthesis 1 forthe medical device proposed by the invention will be described first ofall with reference to FIG. 1a to 1e . FIG. 1a illustrates theendoprosthesis 1 in its first pre-definable mode in which theendoprosthesis is in a minimised state and can therefore be introducedinto a patient's body with minimal invasion by means of a cathetersystem. FIG. 1c illustrates the endoprosthesis 1 in its second mode inwhich the endoprosthesis is in its expanded state. FIG. 1b illustratesthe endoprosthesis 1 in a state between the first mode (see FIG. 1a )and the second mode (see FIG. 1c ). FIG. 1d illustrates the expandedendoprosthesis of FIG. 1c with a heart valve prosthesis attached to it.The endoprosthesis 1 of this embodiment is distinctive due to the factthat it has a structure which is cut integrally from a metal tube. Thecutting pattern used to produce the stent design is illustrated in aflat projection in FIG. 1 e.

Specifically, the endoprosthesis 1 comprises a total of threepositioning arches 10 which assume the function of automaticallypositioning the medical device in the patient's aorta. The positioningarches 10 have a rounded head portion 12 which engages in the pockets ofthe insufficient heart valve to be replaced by the medical device whenthe medical device is positioned at the implantation site. Providingthree positioning arches 10 in total ensures that the requisitepositioning accuracy can be obtained in the direction of rotation.

The head portions 12 of the positioning arches 10 pointing respectivelytowards the proximal end 3 of the endoprosthesis 1 are appropriatelyrounded so that the vessel wall is not damaged when the positioningarches 10 engage in the pockets of the heart valve to be replaced.Extending from the head portion 12 of the positioning arch 10 to thedistal end 2 of the endoprosthesis 1 are two positioning webs or arms 11in total for each positioning arch 10 which merge into an eye-shapedelement 30 at the distal end 2 of the endoprosthesis 1. This eye-shapedelement 30 serves as a retaining means for attaching the endoprosthesis1 and hence the medical device to an introduction catheter system.

Specifically, the respective retaining eyes 30 are disposed between thetwo arms 11 of two mutually adjacent positioning arches 10. Opening intothe transition portion 13 between the two arms 11 of two mutuallyadjacent positioning arches 10 incorporating the retaining eye 30 is aconnecting web 15 extending essentially in the longitudinal direction ofthe endoprosthesis 1. At the proximal end, the connecting web 15 mergesinto the respective retaining arms 21 of two mutually adjacent retainingarches 20.

As a result of this stent design, an axially symmetrical structure isobtained whereby a retaining arch 20 is associated with each positioningarch 10. The endoprosthesis 1 in the preferred embodiment illustrated inFIGS. 1a to 1c therefore has a total of three retaining arms 20 whichform the base for an anchoring segment of the endoprosthesis 1 foraccommodating a heart valve prosthesis 40 (illustrated in FIG. 1d , forexample). Providing the respective connecting webs 15 between thedistally lying transition portions 23 of two mutually adjacent retainingarches 20 and the transition portions 13 of two mutually adjacentpositioning arches 10 results in a stent structure whereby therespective arms 11 of a positioning arch 10 extend essentially parallelwith the respective arms 21 of a retaining arch 21 associated with thepositioning arch 10.

When the endoprosthesis 1 is in the state illustrated in FIG. 1a , inwhich it assumes its first mode, the respective arms 11 of thepositioning arches 10 directly bound the respective arms 21 of theassociated retaining arches 20.

Particular attention should be paid to FIG. 1c in which theendoprosthesis 1 is illustrated in its second mode. Particularly worthmentioning in respect of this diagram is the fact that every positioningarch 10 and its associated retaining arch 20 has an essentially U-shapedor V-shaped structure which is closed towards the proximal end 3 of theendoprosthesis 1. Specifically, every positioning arch 10 is cut fromthe material portion of the metal tube which is accommodated in theessentially U-shaped or V-shaped structure of the associated retainingarch 20, as may be seen from the cutting pattern illustrated in FIG. 1e.

As may be seen by comparing FIGS. 1a and 1c , during the transition fromthe first mode into the second mode, the endoprosthesis becomes shorterin the longitudinal direction whilst the cross-section simultaneouslybecomes wider, in particular at the distal and the proximal anchoringcircumferential regions 2, 3. When the endoprosthesis 1 is in theexpanded state, the respective positioning arches 10 are specificallyopened out to a more pronounced degree in a radial direction from theplane of the endoprosthesis than is the case at the distal anchoringregion 2 of the stent 1. The positioning arches 10, which assume thefunction of positioning the medical device in the implanted state byengaging in the pockets of the heart valve to be replaced, can thereforeproject further out in a radial direction and can be inserted in theheart valve pockets of the heart valve to be replaced in a particularlyeasy manner.

FIG. 1d illustrates the embodiment in its expanded state with anendoprosthesis 1 of the type illustrated in FIG. 1c and a heart valveprosthesis 40 attached with the aid of a thread 41 and opened out. Asillustrated, opening out the proximal anchoring region 3 of theendoprosthesis 1 in which the heart valve prosthesis 40 is disposedcauses the heart valve prosthesis 40 to open out. A radial force issimultaneously applied to the vessel wall (not illustrated) by theproximal end portions 22 of the retaining arches 21, thereby affording areliable seal of the heart valve prosthesis 40 with respect to thevessel wall.

Although the force exerted by the retaining arches 21 in the radialdirection onto the vessel wall causes the medical device to be securedat the implantation site to a certain extent, the distal anchoringregion 2 is expanded by a further 10% to 25% in the radial directionthan the proximal anchoring region 3 of the endoprosthesis 1 when themedical device is in the expanded state. This allows stable implantationof the medical device, especially in view of the unavoidable peristalticmovement of the vessel wall and the relatively high fluid pressureswhich prevail. As a result, a slightly concave shape is imparted to theendoprosthesis 1 which tapers in the direction of the proximal anchoringregion 3 of the endoprosthesis 1, thereby ensuring that the medicaldevice is firmly anchored in the vessel due to the distal anchoringregion 2 of the endoprosthesis 1 pressing against the vessel wall.

In the embodiment illustrated, the respective arms 21 of the retainingarches 20 have uninterrupted slots or elongate holes 24, the purpose ofwhich is to enable or assist expansion of the endoprosthesis 1 from theminimised state into the expanded state. These slots or elongate holes24 make it easy to widen the cross-section of the stent 1 whilstsimultaneously reducing its length. Naturally, however, it would also beconceivable for these slots or elongate holes 24 to accommodate a thread41 or similar used to attach the heart valve prosthesis 40 (illustratedin FIG. 1d ) to the proximal region 3 of the endoprosthesis 1.

The medical device of the present invention is of a modular designessentially comprising the two separately manufactured components,endoprosthesis 1 and heart valve prosthesis 40. The endoprosthesis 1assumes the function of positioning and securing the heart valveprosthesis 40 in the patient's aorta. It may be preferable if the twocomponents (endoprosthesis 1 and heart valve prosthesis 40) are notconnected to one another until immediately prior to performing thesurgical intervention; this is of advantage in terms of transporting andstoring the endoprosthesis 1 as such since the endoprosthesis 1 is arelatively robust component from a mechanical point of view and can bestored for a significant period of time. This applies in particular ifthe endoprosthesis 1 is stored in its second mode, i.e. in the expandedstate, and is not switched to its first (minimised) mode untilimmediately prior to undertaking the surgical intervention.

FIG. 1a shows the endoprosthesis 1 is in its first mode, in itsminimised state which is the so-called “minimised” mode of theendoprosthesis structure made from a memory shape material. When anexternal stimulus acts on the endoprosthesis body illustrated in FIG. 1a, the shape memory effect is triggered and the fixed open shapememorised during production of the endoprosthesis 1 illustrated in FIG.1c is restored. This external stimulus is preferably a settableswitching temperature and the body must be at a temperature higher thanthe switching temperature in order to trigger the shape memory effectand thus restore the memorised open shape of the endoprosthesis 1. Byselecting the chemical composition of the material used for theendoprosthesis 1, a specific switching temperature can be fixed beforethe endoprosthesis is programmed. In the case of the preferredembodiment the switching temperature lies in a range of between 20° C.and the body temperature of the patient.

Therefore, it would be conceivable for the medical device to be cooledaccordingly during the introduction process. When the medical device hasbeen moved to the desired implantation site, in other words in front ofthe native heart valve, preferably by means of an appropriateintroduction system, cooling can be interrupted so that theendoprosthesis 1 of the medical device is heated to the body temperature(36° C.) of the patient, thereby triggering the shape memory effect ofthe endoprosthesis material. Having triggered the self-expandingproperty of the endoprosthesis 1, radial forces are generated which acton the individual components of the endoprosthesis 1, in particular, onthe respective positioning arches 10, 11 and retaining arches 20, 21 ofthe endoprosthesis 1. Since the endoprosthesis 1 of the medical deviceis still disposed in the introduction catheter system as before, theradial forces which build up once the critical switch temperature isexceeded and act on the individual components of the endoprosthesis 1are compensated by the introduction port of the introduction cathetersystem so that—in spite of the shape memory effect having beentriggered—the endoprosthesis 1 of the medical device is forciblyretained in its first (minimised) mode.

By releasing the endoprosthesis 1 from the introduction catheter systemin appropriate steps, it is then possible to release the positioningarches 10, 11 of the endoprosthesis 1 through the introduction port ofthe introduction catheter system first, as a result of which it opens updue to the radial forces acting in the radial direction. The openedpositioning arches 10, 11 can then be positioned in the pockets of thenative heart valve.

The remaining components of the endoprosthesis 1 and the medical devicecan then be released through the introduction port of the introductioncatheter system. As this happens, the retaining arches 20, 21 open inthe radial direction and the heart valve prosthesis 40 attached to theretaining arches 20, 21 by means of a thread 41, etc., for example, thusunfolds in the manner of an umbrella. The radial forces acting on theretaining arches 20, 21 and also on the distal anchoring region 2 of theendoprosthesis 1 cause the endoprosthesis 1 to be pressed in the radialdirection against the vessel wall. In this way, a reliable anchoring ofthe medical device is guaranteed at the implantation site on the onehand and a reliable seal of the heart valve prosthesis 40 is ensured atthe proximal anchoring region 3 of the endoprosthesis 1 on the otherhand.

FIGS. 2a to 2c illustrate a second embodiment of a self-expandableendoprosthesis 1 for the medical device proposed by the invention in itsfirst, pre-definable mode (see FIG. 2a ) in its second pre-definablemode (see FIG. 2c ) as well as in a state in between (see FIG. 2b ).

FIG. 2d illustrates a second embodiment of the medical device proposedby the invention in its expanded state with an endoprosthesis of thetype illustrated in FIG. 2c and a heart valve prosthesis 40 attached toit and opened out. A flat projection of a cutting pattern which may beused for the production of the second embodiment of the self-expandableendoprosthesis is illustrated in FIG. 2e . This cutting pattern issuitable for cutting the endoprosthesis illustrated in FIG. 2aintegrally from a metal tube.

The endoprosthesis 1 of the second embodiment essentially corresponds tothe first embodiment described above with reference to FIGS. 1a to 1e .Description of the various components corresponds to that described forFIGS. 1a to 1e and will not be repeated. The second embodiment differsfrom the first preferred embodiment of the endoprosthesis in that therespective arms 11 of the adjacent positioning arches 10 are joinedindirectly via a connecting web 16 extending essentially in thelongitudinal direction of the endoprosthesis 1 to the retaining eye 30.The respective arms 21 of the retaining arches 20 are associated withthe adjacent positioning arches 10 are indirectly joined via aconnecting web 15 extending essentially in the longitudinal direction ofthe endoprosthesis 1 to the retaining eye 30. Specifically, theconnecting web 15 of the retaining arches 20 merges into the connectingweb 16 of the positioning arches 10 at the end portion 13 of thepositioning arches 10. By selecting the respective lengths of the twoconnecting webs 15 and 16 accordingly, therefore, the overall length ofthe stent 1 can be adjusted in an easy manner.

The third embodiment of a self-expandable endoprosthesis for the medicaldevice proposed by the invention illustrated in FIGS. 3a to 3cessentially corresponds to the first preferred embodiment illustrated inFIGS. 1a to 1c . The difference, however, is that in the third preferredembodiment, the retaining eyes 30 disposed between two adjacentpositioning arches 10 are provided with barbs 17, the respective tips ofwhich point in the direction of the proximal end 3 of the endoprosthesis1. With this modification to the design additional anchoring is providedfor the system to prevent the stent 1 from being dislocated in thedirection of the left ventricle.

FIG. 3d illustrates a third embodiment of the medical device proposed bythe invention in its expanded state with an endoprosthesis of the typeillustrated in FIG. 3c and a heart valve prosthesis 40 attached to itand opened out. This diagram essentially corresponds to that of FIG. 1d. The difference, however, is that the barb elements 17 described aboveare provided on the respective retaining eyes 30.

A flat projection of a cutting pattern which may be used for theproduction of the third embodiment of the self-expandable endoprosthesis1 is illustrated in FIG. 3e . This cutting pattern is suitable forcutting the endoprosthesis illustrated in FIG. 3a integrally from ametal tube.

FIGS. 4a to 4c illustrate a fourth embodiment of a self-expandableendoprosthesis 1 for the medical device proposed by the invention. Afourth embodiment of the medical device proposed by the invention isillustrated in its expanded state with an endoprosthesis in FIG. 4c andan opened out heart valve prosthesis 40 attached to it is illustrated inFIG. 4d . FIG. 4e illustrates a flat projection of a cutting patternwhich may be used for the production of the fourth embodiment of theself-expandable endoprosthesis 1. The cutting pattern illustrated inFIG. 4e is specifically suitable for cutting the endoprosthesisillustrated in FIG. 4a integrally from a metal tube.

The fourth embodiment of the self-expandable prosthesis 1 corresponds toa combination of the second and third embodiments described above.Specifically, the respective arms 11 of the adjacent positioning arches10 are indirectly joined via the connecting web 16 extending essentiallyin the longitudinal direction of the endoprosthesis to the anchoring eye30. Barbs 17 are provided on the respective anchoring eyes 30, the tipsof which point in the direction of the proximal end 3 of theendoprosthesis 1. The advantages which can be achieved as a result ofthe features provided on the fourth embodiment were described above andwill not be reiterated at this stage.

The fifth embodiment of a self-expandable endoprosthesis 1 and a medicaldevice proposed by the invention illustrated in FIG. 5a to FIG. 5eessentially corresponds to the first embodiment described with referenceto FIG. 1a to FIG. 1e , except that, in this instance, the respectiveretaining arches 21 of the endoprosthesis 1 are provided withreinforcing portions 26 which interrupt the slots 24 extending in thelongitudinal direction of the retaining arches 21. The purpose of thesereinforcing portions 26 is to open out the individual components of theretaining arches 21 and, in particular, to break the anchoring support25 radially out of the retaining arches 20. Accordingly, a retainingportion for the stent 1 can be obtained with the reinforcing portions 26which has no components which might explant the medical device when itis in the expanded state.

FIG. 5e illustrates a flat projection of a cutting pattern which may beused for production of the fifth embodiment of the self-expandableendoprosthesis 1 to cut the endoprosthesis 1 illustrated in FIG. 5aintegrally from a metal tube.

The sixth embodiment of the self-expandable endoprosthesis and themedical device proposed by the invention illustrated in FIGS. 6a to 6ecorresponds to a combination of the second embodiment illustrated inFIGS. 2a to 2e and the fifth embodiment described above with referenceto FIGS. 5a to 5e . Specifically, therefore, the endoprosthesis 1 basedon the second embodiment is provided with additional reinforcingportions 26 at the respective retaining arches 21 which interrupt theslots 24 extending in the longitudinal direction of the retaining arches21.

The seventh embodiment of the endoprosthesis 1 and the medical deviceproposed by the invention illustrated in FIGS. 7a to 7e corresponds to acombination of the third and fifth embodiments described above. Inparticular the respective retaining eyes 30 are provided with barbs 17and the respective retaining arches 21 are provided with reinforcingportions 26.

The eighth embodiment of the self-expandable endoprosthesis and themedical device proposed by the invention illustrated in FIGS. 8a to 8ecorresponds to a combination of the fourth and fifth embodiments, inwhich case the respective retaining arches 21 are provided withreinforcing portions 26. The retaining eyes 30 provided with barbs 17are connected to the respective arms 11 of the adjacent positioningarches 10 by means of a connecting web 16 extending essentially in thelongitudinal direction of the endoprosthesis 1.

The ninth embodiment of the self-expandable endoprosthesis for themedical device proposed by the invention illustrated in FIGS. 9a to 9dis of a slightly modified shape compared with the first embodiment (seeFIGS. 1a to 1c ). The endoprosthesis 1 based on the ninth embodiment isillustrated in its first pre-defined mode in FIG. 9a . FIGS. 9b and 9crespectively show a perspective side view of the endoprosthesis 1 basedon the ninth embodiment in its second mode. Specifically, the connectingweb 15 between the end portion 13 of a positioning arch 10, 11 and theend portion 23 of an associated retaining arch 20, 21 is illustrated inFIG. 9b . FIG. 9c , on the other hand, illustrates the positioningarches 10, 11 and the associated retaining arches 20, 21 of theendoprosthesis 1 illustrated in FIG. 9 a.

FIG. 9e illustrates a flat projection of a cutting pattern which may beused to produce the ninth embodiment of the self-expandableendoprosthesis to cut the endoprosthesis illustrated in FIG. 9aintegrally from a metal tube.

Unlike the first embodiment, the respective head portions 12 of thepositioning arches 10 pointing towards the proximal end 3 of theendoprosthesis are of a slightly wider design at the proximal end in theninth embodiment of the endoprosthesis 1. Although the head portions 12of the positioning arches 10 have a slightly rectangular in shapecompared with the first embodiment, all the respective corners of thehead portions 12 are rounded so that the vessel wall is not damaged whenthe positioning arches 10 engage in the pockets of the heart valve to bereplaced. The advantage of the slightly wider design of the headportions 12 of the positioning arches 10 is that the positioning arches10 can be placed in the pockets of the native heart valve with thesmallest possible clearance during the implantation operation, therebyenabling even more accurate positioning of the medical device at theimplantation site.

As with the embodiments described above, a total of two positioning websor arms 11 extend from the head portion 12 of the positioning arches 10to the distal end 2 of the endoprosthesis 1 for every positioning arch10 in the ninth embodiment of the endoprosthesis 1 and which merge atthe distal end 2 of the endoprosthesis 1 into an eye-shaped element 30.This eye-shaped element 30 serves as a retaining means for attaching theendoprosthesis 1 and hence the medical device to an introductioncatheter system.

Specifically, in the case of the ninth embodiment of the endoprosthesis1, the retaining eyes 30 are disposed between the two arms 11 of twomutually adjacent positioning arches 10. The connecting web 15 extendsessentially in the longitudinal direction of the endoprosthesis 1 andopens into the transition portion 13 between the two arms 11 of twomutually adjacent positioning arches 10 where the retaining eye 30 isformed. At the proximal end of the connecting web 15, the latter mergesinto the respective retaining arms 21 of two mutually adjacent retainingarches 20. This design is illustrated particularly clearly in FIG. 9d ,which shows a perspective plan view of the distal region of theendoprosthesis illustrated in FIG. 9a in its second mode.

In contrast with the embodiments described above, the respectiveretaining arms 21 of the retaining arches 20 on the transition portion23 between the two arms 21 of two mutually adjacent retaining arches 20are not provided with slots or elongate holes 24 in the ninth embodimentof the endoprosthesis 1. Due to the fact that only one arm web 21actually opens into the transition portion 23 between the two arms 21 oftwo mutually adjacent retaining arches 20 for each retaining arch, thereare advantageously no components belonging to the retaining arches 20which project out from the respective retaining arches 20 in a radialdirection when the endoprosthesis 1 is in the expanded state (see FIG.9b for example). When the endoprosthesis 1 is in an expanded state, noanchoring support 25 usually extends through the slots 24 projecting outin a radial direction at the transition portions 23 between the two arms21 of two mutually adjacent retaining arches 20. It has been found that,in this embodiment, the endoprosthesis 1 can be explanted particularlyeasily and removed from the patient's body.

Although the ninth embodiment of the endoprosthesis 1 does not haveslots or elongate holes 24 at the respective transition portions 23between the two arms 21 of two mutually adjacent retaining arches 20,the respective retaining arms 21 of the endoprosthesis 1 havereinforcing portions 26 which are respectively provided on portions ofthe retaining arms 21 that are not congruent with the transitionportions 23 between the two arms 21 of two mutually adjacent retainingarches 20.

FIG. 10 illustrates a flat projection of a cutting pattern which may beused for the production of another embodiment of the self-expandableendoprosthesis 1 to cut an endoprosthesis integrally from a metal tube.The cutting pattern illustrated in FIG. 10 differs from the cuttingpattern illustrated in FIG. 1e due to the fact that the distallydisposed slots 24 extending in the longitudinal direction of theretaining arches 21 have been omitted from the respective retainingarches 21 on the one hand and a bigger space 27 is cut from between theadjacent retaining arches 21 in order to save on material on the otherhand.

FIG. 11 illustrates another embodiment of a self-expandableendoprosthesis 1 for an alternative design of the medical deviceproposed by the invention. Specifically, the endoprosthesis 1 of theembodiment illustrated in FIG. 11 has assumed its second mode in whichthe medical device is in its expanded state. The endoprosthesis 1illustrated in FIG. 11 differs from the endoprosthesis 1 illustrated inFIG. 1c due to the fact that the stent 1 illustrated in FIG. 11 has aninterconnecting web 16 extending essentially in the longitudinaldirection of the endoprosthesis 1 between the retaining eyes 30 and thetransition portion 13 between the positioning arms 11 of two adjacentpositioning arches 10. Thus, the total length of the endoprosthesis 1,and hence the medical device, is made longer. To ensure the optimumability to manoeuvre the medical device in the minimised state, however,it is an advantage if the endoprosthesis 1 has as short a longitudinalextension as possible, especially if the implantation route to the heartvalve leads through the arch of the aorta. It is of advantage if themedical device is as short as possible (and the endoprosthesis 1 is alsoas short as possible) so that the medical device can be manoeuvredeasily around the arch.

The endoprosthesis 1 illustrated in FIG. 11 also differs from theendoprosthesis of the embodiments described above due to the fact thatwhen the endoprosthesis 1 is in the expanded state, a barb portion 25projects through the slots 24 in the radial direction at the respectivetransition portions 23 between the two arms 21 of two mutually adjacentretaining arches 20. The tip of the barb portion 25 points in thedirection of the distal retaining region 2 of the endoprosthesis 1.

A yet further embodiment of the self-expandable endoprosthesis 1 for themedical device proposed by the invention will now be described withreference to FIGS. 17a to 17 b.

FIG. 17a illustrates the endoprosthesis 1 in its first pre-definablemode in which the medical device (not explicitly illustrated) is in aminimised state and can therefore be introduced into a patient's bodywith minimal invasion by means of a catheter system. The endoprosthesis1 in its second mode includes the medical device in its expanded state.FIG. 17b illustrates the stent 50 in a state between the first mode (seeFIG. 17a ) and the second mode. The endoprosthesis 1 in its expandedstate includes a heart valve prosthesis 60 attached to it by sutures.

This embodiment of the self expandable prosthesis 1 correspondsessentially to the second embodiment illustrated in FIGS. 2a-2e . Thedifference with the embodiment illustrated in FIGS. 12a to 12e is thatthe retaining eyes 30 are imperforate, taking the form of retainingheads. It has been found that an imperforate retaining eye allows themedical device to be released more simply and easily from an insertioncatheter system. By way of clarification, it should be noted that it isnot the presence or absence of perforations in the retaining means whichdirectly contribute to the ease of release of the retaining means fromthe catheter. Rather, it is the absence of parts on the catheter onwhich the retaining means may become lodged, passing through orpenetrating the retaining means, for example, such as a peg and hole.

It will be appreciated that the various optional features, includingintegral or extended anchoring eyes 30, barb elements 17, reinforcingportions 26, perforate or imperforate retaining eyes 30, may be used inany combination with the endoprosthesis structure.

A more detailed description will be given below with reference to FIGS.12a and 12b , explaining how the medical device proposed by theinvention is used to treat a condition of heart valve insufficiency.

The medical device proposed by the invention, and in particular theendoprosthesis 1 with the heart valve prosthesis 40 contained in it, isdesigned to be introduced into the patient's body either backwards(retrograde) or transapically, i.e. approaching from the heart apex viaa special catheter. The device is positioned percutaneouslyorthotopically in vivo and assumes the function of an insufficient ornarrowed (stenosed) heart valve. FIG. 13a provides a schematicillustration of one possible implantation operation for the medicaldevice proposed by the invention, whereby the medical device in thisinstance is introduced into the patient's body via a retrograde approachfrom the femoral artery using a special catheter. FIG. 13b provides aschematic view of the medical device proposed by the invention in theimplanted state.

In the case of the implantation route illustrated in FIG. 13a , thecatheter system, which is not specifically illustrated, containing themedical device with the heart valve prosthesis 40 and the endoprosthesis1 serving as an anchoring stent, is introduced by puncturing the A.femoris communis (inguinal artery). This catheter system is preferablymoved forward to the aortal valve position assisted by angiographic(vessel display) and echocardiographic (ultrasound) control, where theactual heart valve implantation then takes place.

Alternatively, a catheter system can be pushed transapically from theheart apex through the left ventricle to the aortal valve where asimilar implantation of the endoprosthesis 1 with the heart valveprosthesis 40 is possible using a catheter suitably modifiedaccordingly.

As the catheter system is introduced, the medical device is preferablycooled, for example by rinsing the interior of the catheter system withan appropriate coolant such as a cooled salt solution. When the medicaldevice has been moved forward to the desired implantation site, coolingis interrupted, as a result of which the endoprosthesis 1 of the medicaldevice is warmed to the body temperature of the patient (36° C.),thereby triggering the shape memory effect of the endoprosthesismaterial.

Due to the triggering of the self-expanding property of theendoprosthesis 1, radial forces develop which act on the individualcomponents of the endoprosthesis 1, in particular on the respectivepositioning arches 10, 11 and retaining arches 20, 21 of theendoprosthesis 1. Since the endoprosthesis 1 of the medical device isstill disposed in the introduction catheter system as before, the radialforces which develop once the critical switching temperature is exceededand act on the individual components of the endoprosthesis 1 so that—inspite of the shape memory effect having been triggered—theendoprosthesis 1 of the medical device is forcibly held in its first(minimised) shape within the closed introduction port of theintroduction catheter system.

By releasing the endoprosthesis 1 from the introduction catheter systemin appropriate steps, the positioning arches 10, 11 of theendoprosthesis 1 are moved out though the introduction port of theintroduction catheter system once opened. The positioning arches 10, 11open out due to the radial forces within the endoprosthesis. The openedpositioning arches 10, 11 are then positioned in the pockets 50 of thenative heart valve 51.

The other components of the endoprosthesis 1 and the medical device arethen released through the introduction port of the introduction cathetersystem. As illustrated in FIG. 13b , the retaining arches 20, 21 opentogether in the radial direction and cause the heart valve prosthesis 40attached to the retaining arches 20, 21 to open out in the manner of anumbrella. However, the radial forces acting on the retaining arches 20,21 also act on the distal anchoring region 2 of the endoprosthesis 1,causing the endoprosthesis 1 to be pressed in a radial direction againstthe vessel wall. This, on the one hand, guarantees a reliable anchoringof the medical device at the implantation site and, on the other hand,ensures a reliable seal of the heart valve prosthesis 40 at the proximalanchoring region 3 of the endoprosthesis 1.

When the medical device is in the implanted state as illustrated in FIG.13b , the heart valve prosthesis 40 is opened out at the proximalanchoring region 3 of the endoprosthesis 1 whilst the old (insufficient)heart valve 51 is pressed towards the vessel wall due to theself-expanding property of the endoprosthesis 1. The distal anchoringregion 2 of the endoprosthesis 1 affords additional mechanical supportfor the system and reliable anchoring.

As may be seen from FIG. 13b , when the endoprosthesis 1 is in itsexpanded state, the respective positioning arms 11 of the positioningarches 10 locate in the pockets of the incumbent heart valve and thusessentially guarantee secure and error-free positioning of the medicaldevice. The pocket flaps of the incumbent heart valve are clampedbetween the positioning arches 10 and the retaining arches 20 due to theexpansion of the endoprosthesis 1. This further assists in achievingoptimum positioning and a stable anchoring of the heart valve prosthesis40. Optimum lateral sealing of the implanted valve prosthesis 40 isguaranteed at the same time.

The system is afforded additional mechanical support and reliableanchoring by providing barbs 17 on the retaining eyes 30 disposed at thedistal anchoring region 2 of the endoprosthesis 1 and/or by appropriateanchoring supports 25. When the endoprosthesis 1 is in the expandedstate, the anchoring supports 25 stand proud of the co-operating arm 21of the retaining arches 20 and their tips point in the direction of thedistal end 2 of the endoprosthesis 1.

The design of the endoprosthesis 1 allows gripping of the endoprosthesis1 by means of the retaining eyes 30 and minimising the medical device bythe longitudinal extension of the endoprosthesis 1 so that the medicaldevice is pulled back into the catheter and removed from the patient'sbody.

Due to the modular integration of retaining elements (retaining eyes) onthe self-expandable endoprosthesis 1, it can also be explanted again byway of a catheter once the endoprosthesis has been implanted. To thisend, the distal anchoring region 2 of the endoprosthesis 1 is pulledinto a catheter by the several retaining eyes using guide wires withinthe catheter. In other words, in the reverse of the implantationoperation, the endoprosthesis 1 is pulled from its expanded state backinto its minimised state and released from the anchoring in the pocketsof the incumbent heart valve. As will be described below the design ofthe endoprosthesis allows reversal of the implantation at any stageduring the implantation process. Specifically explantation may becarried out causing minimal damage and/or stress to the heart, thevasculature and the patient.

Further preferred aspects of the invention will now be described withreference to a catheter insertion system.

Reference to the use of the catheter insertion system specificallydisclosed herein is not intended to necessarily limit the use of thestent with this catheter insertion system alone. It is the novelfeatures of the catheter tip, which could be supplied in the form of amodular cartridge for example, in combination with the retaining means,which afford the increased reliability in terms of stent release andpositioning. Thus such a catheter tip, or cartridge, could be affixed tocatheter systems already known in the art.

With reference to FIGS. 14 and 15, use of the stent with a catheterinsertion system of a transapical design will be explained fortransapical insertion of a self-expandable heart valve stent to apatient's body. FIGS. 14a to d and FIGS. 15a to d respectivelyillustrate an insertion system in its four different pre-definablefunctional modes.

The insertion system 1 is suitable for transapical access to a heartvalve to be replaced, such as an aortal valve for example. Using theinsertion system 1, it is possible to implant a self-expandable heartvalve stent in a patient's body transapically, i.e. from the heart apex.To this end, the insertion system 1 has a catheter system 10, by meansof which the heart valve stent, not explicitly illustrated in FIGS. 14and 15, can be inserted in the patient's body in its minimised mode.FIG. 16 illustrates an embodiment of the catheter tip proposed by theinvention.

In the insertion system 1 illustrated in FIGS. 14 and 15, a catheter tip20 is provided at the proximal end 11 of the catheter system 10, inwhich the heart valve stent to be implanted in the patient's body can beaccommodated. At the distal end 12 of the catheter system 10, a handle30 is also provided, by means of which the catheter tip 20 can bemanipulated.

Specifically, the catheter tip 20 of the insertion system 1 illustratedin FIGS. 14 and 15 has a retaining mechanism 21 so that at least thedistal region of the stent to be implanted in the patient's body can bereleasably attached to the catheter tip. The retaining mechanism will bedescribed in more detail, in particular, with reference to FIG. 16.

The catheter tip 20 also has a housing system for accommodating at leastthe proximal region of the stent. Specifically, the housing systemcomprises a first housing portion 23 for accommodating first functionalcomponents of the stent, for example for accommodating the retainingarches of the stent, and a second housing portion 24 for accommodatingsecond functional components of the stent, for example for accommodatingpositioning arches of the stent.

As regards the handle 30 of the insertion system 1, it has a firstoperating means 33 co-operating with the first housing portion 23 and anoperating means 34 co-operating with the second housing portion. Thefirst operating means 33 of the handle 30 co-operates with the firsthousing portion 23 of the catheter tip 20 so that when the firstoperating means 33 is operated, it causes a pre-definable longitudinalmovement of the first housing portion 23 relative to the fixingmechanism 21. Secondly, the second operating means 34 of the handle 30co-operates with the second housing portion 24 of the catheter tip 20 sothat when the second operating means 34 is operated, it causes apre-definable longitudinal movement of the second housing portion 24 ofthe catheter tip relative to the fixing mechanism 21.

With the insertion system 1, shown in FIGS. 14 to 16 for example, thesecond housing portion 24 of the catheter tip 20 is disposed at theproximal end portion of the catheter tip 20. The first housing portion23 is disposed between the housing portion 24 and the handle 30. Withthis transapical insertion system 1, when the associated secondoperating means 34 of the handle is operated, the second housing portion24 of the catheter tip 20 can be moved in longitudinal direction L ofthe catheter tip 20 relative to the fixing mechanism 21 in the proximaldirection, i.e. away from the handle 30. When the associated firstoperating means 33 of the handle 30 is operated, the first housingportion 23 can be moved in the longitudinal direction L of the cathetertip 20 relative to the fixing mechanism in the distal direction, i.e.towards the handle 30.

The insertion system 1 illustrated in FIGS. 14 to 15 also has a gatesystem 13 co-operating with the catheter system 10 which is connected onthe one hand to the portion of the catheter tip 20 facing the handle andon the other hand to the portion of the handle 30 facing the cathetertip. The gate system 13, which is preferably of a hollow design, has inits interior a first mechanism 26, such as a wire system, to enable aforce to be transmitted from the first operating means 33 of the handle30 to the first housing portion 23 of the catheter tip 20.

The gate system 13 is also provided with a second mechanism 27 fortransmitting force from the second operating means 34 of the handle 30to the second housing portion 24 of the catheter tip 20. As with thefirst force transmitting mechanism 26, the second force transmittingmechanism 27 may be provided in the form of a wire system.

In detail, in the insertion system 1, the second force transmittingmechanism 27, actively connecting the second operating means 34 of thehandle 30 with the second housing portion 24 of the catheter tip 20, isprovided in the form of a wire extending through the interior of thegate system 13. The wire is connected to the second operating means 34of the handle 30 on the one hand and to the second housing portion 24 ofthe catheter tip 20 on the other hand. The first force transmittingmechanism 26 is provided in the form of a sleeve which extends throughthe interior of the gate system 13 and surrounds the wire constitutingthe second force transmitting mechanism 27. The first force transmittingmechanism 26 constitutes an extension of the first housing portion 23 ofthe catheter tip 20 and is actively connected to the first operatingmeans 33 of the handle on the one hand and to the first housing portion23 of the catheter tip 20 on the other hand. Naturally, however, itwould also be conceivable for the first force transmitting mechanism 26to be provided in the form of a sleeve surrounding the wire constitutingthe second force transmitting mechanism 27. In which case the sleeve ofthe first force transmitting mechanism 26 simultaneously alsoconstitutes the gate system 13 and is an extension of the first housingportion 23 which is actively connected to the first operating means 33of the handle on the one hand and to the first housing portion 23 of thecatheter tip 20 on the other hand.

The gate system 13 or the sleeve of the first force transmittingmechanism 26 used with the catheter system 10 of the transapical designof the insertion system 1 is provided in the form of an elongate tubeand the second force transmitting mechanism 27. Optionally, the firstforce transmitting mechanism 26 is disposed in the interior of thistube. The gate system 13 is preferably designed so that its lengthremains virtually unchanged, especially when subjected to thecompression or tensile stress which occurs during the process ofinserting the catheter system 10. This function of the gate system 13 isachieved by using an appropriate material for the elongate tube and byan expedient choice of the wall thickness. In particular, it ispreferable if the gate system 13 or the sleeve of the first forcetransmitting mechanism 26 is both resistant to buckling and alsoflexible so that a bending radius of at least 4 cm and preferably atleast 3 cm can be achieved with the gate system 13, at least in theproximal region 14 of the gate system 13.

As regards the fixing mechanism 21 belonging to the catheter tip 20 inthe illustrated embodiment of the transapically designed insertionsystem 1, this fixing mechanism 21 is provided in the form of a crown 21a with a total of three pockets 22 formed therein. The pockets 22 of thecrown 21 a are of a design complementing retaining elements, for exampleretaining heads, which are disposed at a distal region of the stentwhich is to be accommodated or can be accommodated in the catheter tip20 of the insertion system 1. The pockets 22 formed in the crown 21 aestablish a releasable engagement with the distal region of the stent sothat the stent can be releasably attached to the retaining mechanism 21of the catheter tip 20.

As may be seen in particular from FIGS. 14 and 15, in the embodiment ofthe illustrated transapically designed insertion system 1, both thefirst housing portion 23 of the catheter tip 20 and the second housingportion 24 of the catheter tip 20 are each provided in the form ofsleeves or sleeve-type portions and are specifically designed toaccommodate the functional components of the stent. Specifically, theinternal diameter of the second sleeve-type housing portion 24 is biggerthan the external diameter of the first sleeve-type housing portion 23.Accordingly, in the case of the embodiment of the illustratedtransapically designed insertion system 1, the second housing portion 24of the catheter tip 20 is designed to accommodate, in addition to thesecond functional components of the stent, namely the positioning archesof the stent, the first housing portion 23 of the catheter tip 20 withthe first functional components of the stent accommodated in it, namelythe retaining arches of the stent.

Turning to the handle 30 used with the embodiment of the insertionsystem 1 illustrated in FIGS. 14 and 15, the illustrated embodiment ofthe insertion system 1 is such that the second operating means 34, whichco-operates with the second housing portion 24 of the catheter tip 20via the second force transmitting mechanism 27, has a carriage which isguided in a guide 31′ and actively connected to a slide 31″. Thecarriage of the second operating means 34 is actively connected to thesecond housing portion 24 of the catheter tip 20 co-operating with thesecond operating means 34 via the second force transmitting mechanism 27so that when the second operating means 34 is operated, in particularthe carriage of the second operating means 34, a force is transmitteddirectly from the carriage of the second operating means 34 to thesecond housing portion 24 of the catheter tip 20. In the same way, thefirst operating means 33, which is actively connected to the firsthousing portion 23 of the catheter tip 20 via the first forcetransmitting mechanism 26, also has a carriage which is guided in aguide 32′ and is actively connected to another slide 32″. The carriageof the first operating means 33 is actively connected to the firsthousing portion 23 of the catheter tip 20 co-operating with the firstoperating means 33 via the first force transmitting mechanism 26. Thus,when the first operating means 33 is operated, in particular when thecarriage of the first operating means 33 is operated, a force istransmitted directly from the carriage of the first operating means 33to the first housing portion 23 of the catheter tip 20.

As regards the first operating means 33 of the handle 30 used with theinsertion system 1 illustrated in FIGS. 14 and 15, the handle 30 alsohas a first and a second stop 35, 36. These stops co-operate with thefirst operating means 33 and are designed to fix the total stroke lengthof the longitudinal movement of the first housing portion 23 of thecatheter tip 20 when the operating means 33 is operated. This isachieved by the fact that the displacement path which can be covered bythe slide of the first operating means 33 on the guide 32′ is fixed.

The handle 30 also has a third and fourth stop 37, 38 which co-operatewith the second operating means 34 and fix the total stroke length ofthe longitudinal movement. This can be effected by the second housingportion 24 of the catheter tip 20 when the second operating means 34 isoperated.

In addition to the third and fourth stops 37, 38, the handle 30 of theembodiment of the insertion system 1 illustrated in FIGS. 14 and 15 alsohas another, fifth stop 39 co-operating with the second operating means34. This stop co-operates with the third stop 37 on the one hand andwith the fourth stop 38 on the other hand. When the second operatingmeans 34 is operated, a stepped longitudinal movement comprising twoindividual steps of the carriage on the guide 31′ of the secondoperating means 34 is effected and thus a stepped longitudinal movementoccurs comprising two individual steps of moving the second housingportion 24 of the catheter tip 20 relative to the fixing mechanism orcrown 21 of the catheter tip 20.

Since the fifth stop 39 co-operating with the second operating means 34is expediently positioned on the guide 31′ of the second operating means34 between the third stop 37 and the fourth stop 38. The third and fifthstops 37, 39 on the one hand and the fourth and fifth stops 38, 39 onthe other hand fix the stroke length of the longitudinal movement of thesecond housing portion 24 of the catheter tip 20 for each individualstep when the second operating means is operated.

As illustrated in FIGS. 14 and 15, in the illustrated embodiment of theinsertion system 1, the above-mentioned fifth stop 39 of the handle 30co-operating with the second operating means 34 of the handle 30 isprovided in the form of a stop element 44 releasably secured to theguide 31′ of the carriage belonging to the second operating means 34.

Finally, the handle 30 of the insertion system 1 illustrated in FIGS. 14and 15 is such that both the first operating means 33 and the secondoperating means 34 are each assigned a locking element 41, 42.Specifically, the first locking element 41, co-operating with the firstoperating means 33 of the handle 30, is provided in the form of alocking element which can be removed from the carriage or from the slide32″ of the first operating means 33. The locking element 41 co-operateswith the first operating means 33 and with the carriage of the firstoperating means 33 so that a longitudinal movement of the first housingportion 23 of the catheter tip 20, which can be effected by means of thefirst operating means 33, can be blocked. The second locking element 42on the other hand, which co-operates with the second operating means 34,is also provided in the form of a locking element which can be removedfrom the carriage or from the slide 31″ of the second operating means34. The locking element co-operates with the second operating means 34so that a longitudinal movement of the second housing portion 24 of thecatheter tip 20, which can be effected by means of the second operatingmeans 34, can be blocked.

The four different functional modes which can be achieved with theinsertion system 1 will be described below with reference to FIGS. 15ato 15 d.

FIG. 15a illustrates the insertion system 1 in its first functionalmode, in which the catheter tip 20 is completely closed. As mentionedabove, a self-expandable heart valve stent can be accommodated in thecatheter tip 20 or in the corresponding housing portions 23 and 24 ofthe catheter tip 20.

In the first functional mode illustrated in FIG. 15a , the respectiveslides 31″ and 32″ and hence the respective carriages of the second andfirst operating means 34 and 33 are each in their first position (pos.1). Specifically, the slide 32″ of the first operating means 33 liesagainst the first top 35 provided at the catheter tip end of the guide32′. In this first position, the slide 32″ is fixed by means of thefirst locking element 41 so that a longitudinal movement of the slide32″ and the carriage of the first operating means 33 on the guide 32′ isblocked in the direction of the second stop 36 co-operating with thefirst operating means 33.

The slide 31″ and the carriage of the second operating means 34 are alsolying in the first functional mode illustrated in FIG. 15a , likewise inthe first position (pos. 1) on the third stop 37 of the second operatingmeans 34. The third stop of the second operating means 34 is disposed atthe distal end of the guide 31′ of the second operating means 34. Inthis first position, the slide 31″ and the carriage of the secondoperating means 34 are fixed by means of the second locking element 42in order to block a longitudinal movement of the slide 31″ and carriagealong the guide 31′ in the direction towards the catheter tip.

As mentioned above, when the insertion system 1 is in the firstfunctional mode as illustrated in FIG. 15a , the catheter tip 20 of theinsertion system 1 is in a completely closed mode. In this mode, thefirst and second housing portions 23 and 24 of the catheter tip 20,provided in the form of sleeve-shaped elements, engage telescopicallyone inside the other. This feature is achieved by adapting therespective internal and external diameters of these sleeve-shapedelements to one another accordingly. Specifically, the sleeve-typesecond operating means 34 has an external diameter which is preferablyidentical to the external diameter of the proximal region 14 of the gatesystem 13. As will be described in more detail below, the sleeve-typefirst and second housing portions 23 and 24 of the catheter tip 20 areadapted to one another in terms of their respective internal andexternal diameters so that the folded retaining arches of the stent tobe accommodated in the catheter tip 20 with the heart valve prosthesisattached to it can be accommodated in the sleeve-shaped first housingportion 23 and can be held in their folded or minimised mode. At thesame time, the folded positioning arches of the stent are accommodatedbetween the sleeve-shaped first housing portion 23 and the sleeve-shapedsecond housing portion 24 of the catheter tip 20 and held in theirfolded mode.

In the first functional mode of the insertion system 1, the catheter tip20 is inserted in the patient's body and guided to the desiredimplantation site. In the case of the insertion system 1 based on thefirst embodiment of the solution proposed by the invention, illustratedin FIG. 15a , the implantation site, i.e. the incumbent heart valve, canbe accessed transapically, in other words from the heart apex, becauseat the proximal region of the catheter tip 20 the retaining mechanism isprovided in the form of the crown 21, whilst the first housing portion23 of the catheter tip 20 is disposed distally with respect to it.

FIG. 15b shows the insertion system 1 illustrated in FIG. 15a in itssecond functional mode. This second functional mode is assumedimmediately the catheter tip 20 of the insertion system 1 has reachedthe implantation site in the patient's body. As will be explained inmore detail with reference to FIGS. 15b to 15d , once the catheter tip20 has reached the implantation site, the requisite manipulations of theindividual housing portions 23, 24 of the catheter tip which are neededto release the stent accommodated in the catheter tip 20 in a predefinedsequence of events in steps are effected so that the differentfunctional components of the stent, in particular the positioning archesand the retaining arches of the stent, are released in sequence. Steppedrelease of the endoprosthesis accommodated in the catheter tip 20 of theinsertion system 1 by specific movements of the individual housingportions 23 and 24 of the catheter tip 20 will be explained in detailbelow.

Once the catheter tip 20 has reached the implantation site, theinsertion system 1 is switched from the first functional modeillustrated in FIG. 15a to the second functional mode illustrated inFIG. 15b by operating the second operating means 34. Specifically, thesecond locking element 42 is removed from the second operating means 34,as a result of which the longitudinal movement of the slide 31″ and thecarriage of the second operating means 34 is no longer blocked.

After removing the second locking element 42 from the second operatingmeans 34 and after releasing the lock of the slide 31″ and the carriage31 of the second operating means 34, the slide 31″ and carriage 31 ofthe second operating means 34 are moved along the guide 31′ in thedirection of the catheter tip 20 from the first position (pos. 1) to thesecond position (pos. 2). The second position (pos. 2) is determined bythe fifth stop 39 disposed between the third stop 37 (pos. 1) and thefourth stop 38.

By operating the second operating means 34 in this way, the secondhousing portion 24 of the catheter tip 20 co-operating with the secondoperating means 34 is moved in the proximal direction relative to theretaining mechanism 21 of the catheter tip 20. The amount of movement,i.e. the extent of the longitudinal movement of the second housingportion 24 of the catheter tip 20 relative to the fixing mechanism 21 ofthe catheter tip 20 in the proximal direction in this instance, is fixedby the stroke length of the longitudinal movement which can be effectedbetween the first position (pos. 1) and the second position (pos. 2)effected by the slide 31″ and the carriage using the second operatingmeans 34.

The resultant movement of the second housing portion 24 of the cathetertip 20 relative to the fixing mechanism 21 causes release of thetelescopic engagement between the two sleeve-shaped first and secondhousing portions 23 and 24. The extent of the movement of the secondhousing portion 24 relative to the fixing mechanism 21 or relative tothe first housing portion 23, and hence the stroke of the longitudinalmovement which can be effected by the slide 31″ and carriage using thesecond operating means 34, is selected so that the sleeve-shaped secondhousing portion 24 of the catheter tip 20 no longer surrounds the firsthousing portion 23 of the catheter tip 20 telescopically but stillcovers the retaining mechanism 21 or crown 21 a, in particular thepockets 22 formed in the crown 21 a. As a result, in the secondfunctional mode of the insertion system 1, as illustrated in FIG. 17b ,the distal retaining region of the heart valve stent accommodated in thecatheter tip 20 is held fixed by the catheter tip 20, in particular bythe retaining mechanism 21. This is achieved because the retainingheads, etc., provided at the distal end of the stent are engaged withthe pockets 22 formed in the crown 21 a of the retaining mechanism 21.

As will be explained in more detail below with reference to FIG. 17,when the insertion system 1 is in the second functional mode illustratedin FIG. 15b , the retaining arches of the stent are still held in theirminimised mode by the first housing portion 23 of the catheter tip 20.This is because these components of the stent are accommodated in thefirst housing portion 23 of the catheter tip 20. Engagement between theretaining heads at the distal end of the stent and the pockets 22 formedin the crown 21 a of the retaining mechanism 21 is secured by means ofthe distal end of the second housing portion 24 so that the distalretaining region of the stent is also still held in its minimised modeby the second housing portion 24. As already explained, this is madepossible because the distal end of the second housing portion 24 isstill covering the crown 21 a and the retaining mechanism 21 with thepockets 22 formed therein and the retaining heads of the stentaccommodated in the pockets 22.

By manipulating the second operating means 34, the second housingportion 24 of the catheter tip 20 is moved away from the handle 30 inthe proximal direction relative to the retaining mechanism 21 and to thefirst housing portion 23 of the catheter tip 20 so that the positioningarches of the stent are no longer covered by the second housing portion24. In other words, due to the longitudinal movement of the secondhousing portion 24, when the insertion system 1 is in the secondfunctional mode, the telescopic hold of the positioning arches of thestent between the first and the second housing portions 23 and 24 of thecatheter tip 20 achieved in the first functional mode (see. FIG. 15a )is released. When the insertion system 1 is in the second functionalmode (see. FIG. 15b ), the second housing portion 24 of the catheter tip20 no longer assumes the function of holding the positioning arches ofthe stent in their minimised mode so they are released and are able tounfold accordingly. As illustrated in detail in FIG. 17, the positioningarches of the stent open up once they have been released because of theinherent radial forces in the stent structure. These opened positioningarches can then be positioned in the pockets of the incumbent heartvalve.

Once the positioning arches of the stent have been positioned in thepockets of the incumbent heart valve, the insertion system 1 istransferred from the second functional mode illustrated in FIG. 15b tothe third functional mode illustrated in FIG. 15c . This is achieved byremoving the first locking element 41 co-operating with the firstoperating means 33 of the handle 30 and thus releasing the lock,allowing the slide 32″ and the carriage of the first operating means 33to effect a longitudinal movement.

Once the first locking element 41 has been removed, the slide 32″ andcarriage of the first operating means 33 are moved along the guide 32′from the first position (pos. 1) into the second position (pos. 2). Thestroke of the longitudinal movement is fixed by the second stop 36 ofthe first operating means 33 disposed at the distal end of the guide 32′of the first operating means 33.

By manipulating the first operating means 33, the first housing portion23 of the catheter tip 20 co-operating with the first operating means 33is moved by the stroke of the longitudinal movement. This is effected bythe slide 32″ and carriage of the first operating means 33 relative tothe retaining mechanism 21 of the catheter tip 20 and to the secondhousing portion 24 in the distal direction towards the handle 30. Withthis movement of the first housing portion 23 of the catheter tip 20relative to the retaining mechanism and crown 21 a, the first housingportion 23 is no longer covering the proximal anchoring region of thestent and therefore releases the retaining arches of the stent, togetherwith the heart valve prosthesis attached to it. This is due to anexpedient selection of the stroke of the longitudinal movement which canbe achieved by the first operating means 33. The release of the proximalanchoring region of the stent causes the proximal anchoring region ofthe stent to unfold completely by virtue of the radial forces acting onit.

When the insertion system 1 is in the third functional mode, asillustrated in FIG. 15c , the distal end of the second housing portion24 of the catheter tip 20 is still covering the retaining mechanism 21or the crown 21 a. The engagement of the stent retaining heads inpockets 22 formed in the crown 21 a continues to exist so that the stentremains actively connected to the catheter system 10 of the insertionsystem 1. In spite of the fact that its proximal anchoring region hasunfolded, the stent with the heart valve prosthesis attached to it canstill be retracted back into the catheter and explanted. Explantationtakes place in a corresponding sequence but in reverse, whereby theinsertion system 1 is firstly switched from the third functional mode tothe second functional mode and then to the first functional mode.

Once the proximal anchoring region of the stent has been fully releasedand after checking that the unfolded heart valve prosthesis isfunctioning correctly, the stent can be released from the catheter tip.This is achieved by switching the insertion system 1 from its thirdfunctional mode illustrated in FIG. 15c to the fourth functional modeillustrated in FIG. 15d . If any abnormalities are found during thecheck the stent may be explanted as described above.

In the fourth functional mode, the catch element or locking element 44provided between the third stop 37 and fourth stop 38 on the guide 31′of the second operating means 34, which defines the fifth stop 39 in thesecond functional mode illustrated in FIG. 14b , has been removed. As aresult, the slide 31″ and carriage of the second operating means 34 canbe moved farther in the direction of the catheter tip 20 of theinsertion system 1 on the guide 31′, from the second position (pos. 2)into the third position (pos. 3). This third position (pos. 3) isdefined by the fourth stop 38 at the proximal end of the guide 31′ ofthe second operating means 34. Accordingly, a predefined (additional)movement of the carriage of the second operating means 34 is effected.As a result, the second housing portion 24 of the catheter tip 20co-operating with the second operating means 34 is moved relative to theretaining mechanism 21 further in the proximal direction, away from thehandle 30, due to the stroke of the longitudinal movement caused by theadditional manipulation of the second operating means 34.

The stroke of the longitudinal movement caused by the additionalmanipulation of the second operating means 34 is selected so that whenthe second housing portion 24 of the catheter tip 20 is moved relativeto the retaining mechanism 21, at least the pockets 22 formed in thecrown 21 a of the retaining mechanism 21 are no longer covered by thedistal end of the second housing portion 24. This uncovering of thepockets 22 of the retaining mechanism 21 by the second housing portion24 causes release of the engagement between the retaining heads providedat the distal end of the stent and the pockets 22 of the retainingmechanism 21. This, in turn, causes the distal retaining region of thestent to be released completely and thus leads to a complete unfoldingof the stent.

FIGS. 14a to 14d illustrate the insertion system 1 in its four differentfunctional modes described with reference to FIGS. 15a to 15d . However,this time, the diagrams start with the fourth functional mode (FIG. 14a) and then show the third functional mode (FIG. 14b ), the secondfunctional mode (FIG. 14c ), ending with the first functional mode (FIG.14d ). The sequence illustrated in FIG. 14 is used to load a stent, suchas that illustrated in FIG. 17 for example, into the catheter tip 20 ofthe insertion system 1. The loading procedure, in the steps illustratedin FIGS. 14a to 14d , corresponds to the sequence of the procedureillustrated in FIGS. 15a to 15d but in reverse and is used to remove astent accommodated in the catheter tip 20 of the insertion system 1. Toavoid repetition, reference may be made to the explanations given withrespect to FIGS. 15a to 15 d.

A preferred embodiment of the retaining mechanism 21 disposed in thecatheter tip 20 of the insertion system proposed by the invention willbe described in detail below with reference to FIG. 16.

FIG. 16a is a side view showing a preferred embodiment of the retainingmechanism 21. FIG. 16b is a view in cross-section along line A-Aindicated in FIG. 16a , illustrating the embodiment of the retainingmechanism 21, whilst FIG. 16c shows a plan view of the distal retainingregion 52 of a stent 50 which can be retained in the catheter tip 20 ofthe insertion system proposed by the invention by means of the retainingmechanism 21 based on the embodiment illustrated in FIG. 16 a.

As illustrated, the retaining mechanism 21 has an essentiallycylindrical body 21 a, the axis of symmetry of which lies on thelongitudinal axis L of the catheter tip 20. Several cut-outs or pockets22—in FIG. 16b three in total—are spaced uniformly apart from oneanother in the material of the retaining mechanism body 21 a, preferablyat the proximal end portion of the cylindrical body 21 a. These pockets22 are connected to the proximal-end surface of the cylindrical body 21a by grooves 21 b.

The shape and size of the pockets 22 a in the material of the body orcrown 21 a of the retaining mechanism 21 are selected so that aretaining element 55 of the stent 50 complementing the pocket 22 a canbe accommodated, preferably positively, in each of the pockets 22 a.Thus, each retaining element 55 of the stent 50 establishes a releasableengagement with a pocket 22 a formed in the crown 21 a of the retainingmechanism 21.

As illustrated in FIG. 16c , it is preferable in this respect if theretaining elements 55 of the stent 50 are provided in the form ofprojecting elements or projecting heads (retaining heads) at the distalend 52 of the stent 50. These retaining elements 55 of the stent 50 inthe form of projecting elements are each connected to the positioningarches 54 (and retaining arches 53) of the stent 50 via a neck portionor connecting web 56. When the retaining elements 55 of the stent 50 arepositively held in the pockets 22 a of the retaining mechanism 21, atleast the distal ends of the neck portions 56 lie in the grooves 22 b.

Referring to FIG. 15b , the crown 21 a of the retaining mechanism 21 iscylindrical, wherein each of the pockets 22 a formed in the crown 21 aof the retaining mechanism 21 has a shape adapted for substantiallyaccommodating the retaining element 55 provided on the distal region 52of the stent 50 such that there are no parts of the distal region 52 ofthe stent 50 protruding from the superficial surface S of thecylindrical crown 21 a.

In addition, the crown 21 a of the illustrated retaining mechanism 21comprises snap-on means 21 b arranged on the at least one pocket 22 aformed in the crown 21 a of the retaining mechanism 21 for releasablefixing the retaining element 55 provided on the distal region 52 of thestent 50 in the at least one pocket 22 a.

Turning now to FIGS. 17a to 17b , a preferred embodiment of the medicaldevice 100 proposed by the invention will now be described. Asillustrated, the medical device 100 has an insertion system 1 designedfor transapical access, such as that described in detail above withreference to FIGS. 14 and 15. Naturally, however, it would beconceivable for the medical device to be used with an insertion systemdesigned for transarterial access.

In addition to the insertion system 1, the medical device 100 has aself-expandable heart valve stent 50 accommodated in the catheter tip 20of the insertion system 1, to which a heart valve prosthesis to beimplanted is attached, although this is not explicitly illustrated inFIG. 17. In the first functional mode of the insertion system 1illustrated in FIG. 17a , the stent 50 has a first pre-definable mode inwhich it is in a minimised mode. In the implanted mode, on the otherhand, the stent 50 is designed to assume a second pre-definable mode inwhich it is in its expanded configuration.

By using the insertion system 1 described above, the stent 50 istransferred from its first predefined mode into its second predefinedmode sequentially on the basis of a pre-definable sequence of events, insteps, during the implantation process.

Specifically, the stent 50 used with the medical device 100 illustratedin FIG. 16 has a proximal anchoring region 51 to which a heart valveprosthesis is attachable. The stent 50 also has a distal retainingregion 52 with three retaining elements 55 in the form of retainingheads which can be moved into a releasable engagement with the retainingmechanism 21 of the insertion system 1 and in particular with thepockets 22 a formed in the crown 21 a of the retaining mechanism 21 ofthe insertion system 1.

In addition to the proximal anchoring and distal retaining regions 51,52, the stent 50 also has three first functional components 53 in theform of retaining arches for accommodating the heart valve prosthesisand three second functional components 54 in the form of positioningarches for automatically positioning the stent 50 at the implantationsite. The respective positioning arches 54 of the stent 50 are of afunctional and structural design such that during the implantationoperation and when the stent 50 is in the implanted mode, especiallyfrom the point when the insertion system 1 is in the second functionalmode, they engage in the pockets of the incumbent heart valve. Thisbeing the case, each positioning arch 54 of the stent 50 co-operateswith a retaining arch 53, and at the distal region 52 of the stent 50,each end portion 57 of the respective positioning arches 54 is joined tothe end portion 58 of the co-operating retaining arch 53.

Specifically, every positioning arch 54 and its co-operating retainingarch 53 of the stent 50 is respectively of an essentially U-shaped orV-shaped structure, which is closed towards the proximal end 51 of thestent 50.

The procedure involved in implanting the stent 50 will now be describedin detail with reference to FIGS. 17a to 17b . Specifically, FIG. 17aillustrates the proximal end of a catheter system 10 with the cathetertip 20 and the stent 50 accommodated in the catheter tip 20 with theinsertion system 1 in the first functional mode. As already described inconnection with FIG. 15a , when the insertion system 1 illustrated inFIG. 17a is in its first functional mode in which the retaining heads 55of the stent 50 are engaged with the pockets 22 a formed in the crown 21a of the retaining mechanism 21 of the catheter tip 20 of the insertionsystem 1, the retaining arches 53 of the stent with the heart valveprosthesis attached to it are accommodated in the sleeve-shaped firsthousing portion 23 of the catheter tip 20. When the insertion system 1is in the first functional mode, the positioning arches 54 of the stent50 lie between the sleeve-shaped first housing portion 23 and thelikewise sleeve-shaped second housing portion 24 of the catheter tip 20.The two housing portions 23 and 24 of the catheter tip 20 are of amutually telescopic design. Specifically, the sleeve-shaped secondhousing portion 24 of the catheter tip 20 covers the distal retainingregion 52 of the stent 50, the positioning arches 54 of the stent 50 andthe sleeve-type first housing portion 23 of the catheter tip 20, inwhich the proximal anchoring region 51 of the stent 50 with theretaining arches 53 and the heart valve prosthesis 60 (not illustratedin FIG. 17) are accommodated.

As explained above, the material used for the stent is a shape memorymaterial and the shape memory effect and hence the open shape of thestent 50 is triggered by the effect of an external stimulus. Byparticular preference, this external stimulus is a pre-settableswitching temperature which means that the stent material has to beheated to a temperature that is higher than the switching temperature totrigger the shape memory effect and thus restore the memorised openshape of the stent 50. In view of the application for which the medicaldevice 100 is used, it is preferable if the switching temperature is inthe range of room temperature and the patient's body temperature.Accordingly, care must be taken when implanting the stent 50 that thestent 50 is appropriately cooled, for example by means of a syringeadapter 43 provided in the handle 30, thereby enabling the cathetersystem 10 and the catheter tip 20 of the insertion system 1 to be rinsedwith an appropriate coolant, such as a salt solution.

In the mode illustrated in FIG. 17a , the catheter tip 20 is fedforwards transapically, i.e. from the heart apex, to the diseased orfailing native heart valve.

When the catheter tip 20 with the stent 50 accommodated in the cathetertip 20 has been moved forward to the desired implantation site, coolingis interrupted, as a result of which the stent 50 is heated to thepatient's body temperature (36° C.), thereby triggering the shape memoryeffect of the stent material.

Due to the self-expanding property of the stent 50 triggered as aresult, radial forces build up which act on the individual components ofthe stent 50 and, in particular, on the respective positioning arches 54and retaining arches 53 of the stent. Since the retaining arches 53 ofthe stent 50 are still accommodated in the sleeve-type first housingportion 23 of the catheter tip 20 as before, the retaining arches 53 ofthe stent 50 and the proximal anchoring region 51 of the stent 50 areheld in the minimised mode, in spite of the fact that the shape memoryeffect has been triggered. The positioning arches 54 of the stent 50 andthe distal retaining region 52 of the stent 50 are therefore forciblyretained in their folded mode by the sleeve-shaped second housingportion 24.

On reaching the implantation site, the positioning arches 54 of thestent 50 are then released due to an appropriate stepped release of thestent 50 from the insertion system 1. This is done by transferring theinsertion system 1 from its first functional mode (see FIG. 15a ) to itssecond functional mode (see FIG. 15b ) as described in detail above withreference to FIG. 15a and FIG. 15b , for example and individuallyillustrated in FIG. 17b . By manipulating the second operating means 34of the handle 30 used with the insertion system 1, the second housingportion 24 of the catheter tip 20 is moved relative to the retainingmechanism 21 and to the distal retaining region 52 of the stent 50 inthe proximal direction, in other words away from the handle. The strokeof the longitudinal movement of the sleeve-type second housing portion24 effected as a result relative to the retaining mechanism 21 of thecatheter tip 20 leads to a situation in which the positioning arches 54of the stent 50 are no longer surrounded by the sleeve-shaped secondhousing portion 24 of the catheter tip 20. As a result, theself-expanding property of the positioning arches 54 of the stent 50opens them due to the radial forces acting in the radial direction. Theopened positioning arches 54 of the stent 50 are then positioned in thepockets of the incumbent heart valve. As explained above, the cathetertip 20 of the insertion system 1 can rotate about the longitudinal axisL of the catheter tip 20, which makes positioning of the unfoldedpositioning arches 54 of the stent 50 in the pockets 70 of the nativeheart valve easier.

Once the partially expanded stent 50 has been positioned in the pocketsof the incumbent heart valve, the insertion system 1 is switched fromthe second functional mode illustrated in FIG. 17b to the thirdfunctional mode. The way in which the insertion system 1 is switchedfrom the second functional mode to the third functional mode wasexplained in detail above with reference to FIG. 15c . The proximalanchoring region 51 of the stent 50 is released from the first housingportion 23 of the catheter tip 20 when the insertion system 1 is in thethird functional mode. The released retaining arches 53 of the stent 50and the proximal anchoring region 51 of the stent 50, released when theinsertion system 1 is in the third functional mode, open due to theradial forces acting in a radial direction and unfold the heart valveprosthesis attached to the retaining arches 53 in the manner of anumbrella.

A check may be made to ensure that the already unfolded heart valveprosthesis is functioning correctly. Once the functioning of the heartvalve prosthesis 60 has been checked, the insertion system 1 can then beswitched from its third functional mode to its fourth functional mode byanother manipulation of the second operating means 34 of the handle 30of the insertion system 1. The way in which the insertion system 1 isswitched to the fourth functional mode was described above withreference to FIG. 15 d.

When the second housing portion 24 of the catheter tip 20 is movedfurther in the proximal direction, in other words away from the handle30, the distal end portion of the sleeve-type second housing portion 24of the catheter tip 20 is moved further in the proximal direction sothat this distal part of the second housing portion 24 is no longercovering the pockets 22 a formed in the crown 21 a of the retainingmechanism 21. Accordingly, the hold on the distal retaining region 52 ofthe stent 50 by the catheter tip 20 is released so that the distalretaining region 52 of the stent 50 also expands in the radialdirection, thereby causing the stent 50 to unfold completely.

If, on checking the functioning of the already unfolded heart valveprosthesis in the third functional mode of the insertion system 1, it isascertained that the implanted heart valve prosthesis is not able tofulfil its function or is not able to do so satisfactorily, or if thestent 50 has not been or can not be optimally positioned at theimplantation site, it is possible to switch the insertion system 1 backto the second and then the first functional mode again by moving theco-operating housing portions 23, 24 of the catheter tip 20 in theopposite direction. As a result, the already released and expandedcomponents of the stent 50 can be moved back into the respective housingportions 23, 24 of the catheter tip 20 so that the catheter tip 20 andthe stent 50, accommodated in the catheter tip 20 again, can be removedfrom the patient's body. By returning the stent back into the catheter,damage to vascular system on removal of the stent from the body isminimised.

When the stent 50 has been implanted, the retaining arches 53 of thestent open out in the radial direction, during which the radial forcesacting on the retaining arches 53 and also on the distal retainingregion 52 of the stent 50 cause the stent 50 to be pressed in a radialdirection towards the vessel wall. This provides a reliable anchoring ofthe stent 50 with the heart valve prosthesis attached to it at theproximal anchoring region 51 at the implantation site and substantiallyguarantees a reliable seal of the heart valve prosthesis at the proximalanchoring region 51 of the stent 50.

When the heart valve prosthesis is in the implanted mode, the incumbentheart valve is pressed towards the vessel wall due to the self-expandingproperty of the stent 50. Specifically, the pocket flaps of theinsufficient or stenosed heart valve are clamped between the positioningarches 54 and the retaining arches 53 due to the expansion of the stent50. This permits optimal positioning and stable anchoring of the heartvalve prosthesis disposed on the proximal anchoring region 51 of thestent 50.

The above-discussed stent designs, which constitute the basis of themedical device 100 in conjunction with the insertion system 1, areparticularly suitable for insertion in a patient's body with minimalinvasion using the insertion system 1.

The solution proposed by the invention is distinctive due to an improvedinsertion system with a stent which can be accommodated in the cathetertip of the insertion system. The stent may be inserted from atransarterial or transapical approach by means of the special insertionsystem and optimally positioned so that the heart valve prosthesis,stitched to the proximal anchoring region of the stent, can assume thefunction of the insufficient, narrowed or calcified native heart valve.The radial forces which build up due to the self-expanding property ofthe stent substantially guarantee a reliable anchoring in the region ofthe aorta. The catheter system of the insertion system is preferably an18 to 21F insertion unit, which is compatible with 21F insertion gatesand a 0.035″-guide wire. The length of the catheter system should be atleast 100 cm in the case of the insertion system designed fortransarterial access. The deflecting mechanism which may optionally beprovided in the proximal region of the gate system 13 is preferablyapproximately 30 cm.

The solution proposed by the invention is based on a metalendoprosthesis 1 with a heart valve prosthesis which can be stitched toit or is stitched to it, designed for use in treating diseases of theheart valve which make replacement of the incumbent heart valvenecessary. The heart valve stent 1 (endoprosthesis) may be introduced inthe inverted position and thus positioned orthotopically in vivopercutaneously and assumes the function of the insufficient or defectivenative heart valve. The radial forces created due to the self-expandingproperty of the endoprosthesis 1 substantially guarantee reliableanchoring in the region of the aorta.

A medical instrument comprising an endoprosthesis 1 for positioning andsecuring a heart valve prosthesis in the aorta of the patient isdescribed, together with an endoprosthesis 1 made from a base of Nitinolas a means of accommodating a heart valve prosthesis for implantation inthe body, particularly in the aorta at the site of an aortic heart valvethat requires replacement. The ready-to-use medical device proposed bythe invention consists of the components comprising the self-expandableNitinol stent 1 with the valve-supporting segment 20, valve and systemfor introducing it to the desired site in the body.

In terms of design, the endoprosthesis 1 has three positioning archesfor positioning and fixing the medical device in the vessel of thepatient and retaining webs for accommodating/attaching the heart valveprosthesis by means of a thread, for example. From a functional point ofview, the endoprosthesis 1 exerts high radial forces in its secondexpanded mode to ensure that the medical device is anchored in theaorta. Eyes 30 are preferably provided on the distal retaining region ofthe endoprosthesis 1 or medical device, which can be releasably engagedwith corresponding components of an introduction catheter system.

The material used to trigger the shape memory effect of theendoprosthesis has a switching temperature between 20° C. and 36° C. andis preferably 22° C. In the cooled state, therefore, the medical devicecan be introduced into the patient's body by means of a 21F introductionsystem.

As regards the exact dimensions of the endoprosthesis 1, it is designedto accommodate heart valve prostheses with a valve diameter of 21 mm to25 mm, in which case the distal retaining region 2 of the endoprosthesis1 in particular has a diameter that is approximately 10% to 15% biggerthan this in order to ensure that the medical device is reliablyanchored.

The medical device proposed by the invention has an endoprosthesis whichis readily visible by X-ray, which can be achieved by applying markersat the proximal and/or distal region of the endoprosthesis if necessary.

The materials used for the endoprosthesis 1 are materials that have beentried and tested for implantation purposes, for example Nitinol andTantal. As regards the dimensions of the endoprosthesis, two differentstent sizes are currently preferred, which are set out in the tablebelow together with the diameter of the proximal anchoring region andthe distal retaining region.

Diameter of the proximal Diameter of the distal Stent size anchoringregion retaining region Stent No. 1 21 to 25 mm 32 to 34 mm Stent No. 226 to 31 mm 35 to 38 mm

By applying an appropriate finishing treatment, in particular tempering,other dimensions of the stent can be achieved—starting from the twocurrently preferred stent sizes.

The invention is not restricted to the features described in connectionwith the preferred embodiments illustrated in the drawings. Allcombinations of the features described in the specification would beconceivable.

The invention claimed is:
 1. A method of implanting an endoprosthesisincluding exactly three positioning arches, exactly three retainingarches, exactly three connecting struts, a valve prosthesis directlyattached to each of the exactly three retaining arches, and a pluralityof retaining elements, the method comprising: positioning theendoprosthesis relative to a native valve; manipulating a handle of acatheter to move a first sleeve element to uncover the positioningarches; positioning the positioning arches within pockets of the nativevalve; manipulating the handle to move a second sleeve element touncover the retaining arches to allow the retaining arches and the valveprosthesis to expand, wherein each of the exactly three retaining archesincludes an apex axially aligned along a longitudinal direction of theendoprostesis with a respective apex of one of the exactly threepositioning arches; clamping a plurality of native leaflets of thenative valve between the positioning arches and the retaining arches;and manipulating the handle to further move the first sleeve to uncoverthe plurality of retaining elements; wherein each of the exactly threeconnecting struts connects two of the positioning arches at a firstaxial location along the longitudinal direction and connects two of theretaining arches at a second axial location along the longitudinaldirection, different from the first axial location.
 2. The method ofclaim 1, further including releasing a temporary stop mechanism beforethe step of manipulating the handle to uncover the plurality ofretaining elements.
 3. The method of claim 1, wherein the first sleeveelement is configured to move independently of the second sleeveelement.
 4. The method of claim 1, further comprising moving theendoprosthesis through an aortic arch before the positioning of theendoprosthesis relative to the native valve, wherein the first sleeveelement moves in a first direction to uncover the positioning arches. 5.The method of claim 4, wherein the first sleeve element moves further inthe first direction to uncover the plurality of retaining elements. 6.The method of claim 4, wherein the second sleeve element moves in asecond direction opposite the first direction to uncover the retainingarches.
 7. The method of claim 1, wherein the uncovering of theplurality of retaining elements automatically disengages the pluralityof retaining elements from a plurality of retaining pockets disposedwithin a retaining element of the catheter.
 8. The method of claim 7,wherein each retaining element of the plurality of retaining elementsincludes a rounded head portion connected to a longitudinal strut, andwherein each longitudinal strut connects a pair of adjacent positioningarches of the exactly three positioning arches.
 9. The method of claim1, wherein the positioning arches self-expand when uncovered.
 10. Themethod of claim 1, wherein the endoprosthesis includes at least onemarker element visible by X-ray.
 11. A method of implanting anendoprosthesis including exactly three positioning arches, exactly threeretaining arches, a valve prosthesis directly attached to each of theretaining arches, and a plurality of retaining elements, the methodcomprising: positioning the endoprosthesis relative to a native valve;manipulating a catheter to uncover the positioning arches; positioningthe positioning arches within pockets of the native valve; manipulatingthe catheter to uncover the retaining arches to allow the retainingarches and the valve prosthesis to expand, wherein each of the exactlythree retaining arches includes a plurality of openings through whichthe valve prosthesis is attached, and an apex of each of the retainingarches is axially aligned along a longitudinal direction of theendoprostesis with a respective apex of one of the exactly threepositioning arches; and clamping a plurality of native leaflets of thenative valve between the positioning arches and the retaining arches;wherein, when implanted, the positioning arches are disposed radiallyoutward of the plurality of native leaflets and the retaining arches aredisposed radially inward of the plurality of native leaflets.
 12. Themethod of claim 11, further including manipulating the catheter touncover the plurality of retaining elements, each retaining elementincluding a rounded head portion connected to a longitudinal strutportion, wherein a distal end of the valve prosthesis is proximal to thelongitudinal strut portions of the plurality of retaining elements. 13.The method of claim 11, wherein the positioning arches self-expand whenuncovered.
 14. The method of claim 11, wherein the manipulating of thecatheter to uncover the positioning arches includes manipulating a firstsleeve of the catheter to move in a first direction.
 15. The method ofclaim 14, wherein the manipulating of the catheter to uncover theretaining arches includes manipulating a second sleeve of the catheterto move in a second direction, opposite the first direction.
 16. Themethod of claim 15, further including releasing a temporary lockingelement after the manipulating of the first sleeve and before themanipulating of the second sleeve.
 17. The method of claim 15, furtherincluding manipulating the first sleeve to move further in the firstdirection to uncover the plurality of retaining elements.
 18. The methodof claim 17, further including releasing a temporary locking element onthe catheter after the uncovering of the retaining arches and before theuncovering of the plurality of retaining elements.
 19. The method ofclaim 15, further including releasing a temporary locking element on thecatheter after the uncovering of the positioning arches and before theuncovering of the retaining arches.
 20. A method of implanting anendoprosthesis with a catheter, the endoprosthesis including exactlythree positioning arches, exactly three retaining arches each includingan apex, a valve prosthesis directly attached to each of the exactlythree retaining arches, and a plurality of retaining elements, themethod comprising: positioning the endoprosthesis relative to a nativeaortic valve; moving a first sleeve element in a first direction touncover the positioning arches; positioning the positioning archeswithin pockets of the native aortic valve; moving a second sleeveelement in a second direction to uncover the retaining arches; clampinga plurality of native leaflets of the native aortic valve between thepositioning arches and the retaining arches; and moving the first sleeveelement further in the first direction to uncover the plurality ofretaining elements; wherein the apices of the retaining arches define aproximal-most end of the endoprosthesis; and wherein, when implanted,the positioning arches are disposed radially outward of the plurality ofnative leaflets and the retaining arches are disposed radially inward ofthe plurality of native leaflets.
 21. The method of claim 20, wherein,upon implantation of the endoprosthesis, the apex of each retaining archof the exactly three retaining arches is axially aligned along alongitudinal direction of the endoprosthesis with a respective apex of acorresponding positioning arch of the exactly three positioning arches.22. The method of claim 20, wherein the first direction is away from thesecond sleeve element along a longitudinal axis of the catheter, theplurality of retaining elements remaining covered by the first sleeveelement while the positioning arches are positioned within the pocketsof the native aortic valve.